SPOILER ALERT: This interview contains storyline and character spoilers for "The Grove" episode of "The Walking Dead."

Still trying to digest "The Grove," Sunday's episode of "The Walking Dead"? It was a shocker, with what viewers had seen as troubling behavior by tween Lizzie turn into full-blown tragedy, as Lizzie killed her sister (and was about to kill baby Judith), leaving Carol and Tyreese to decide the only way to deal with Lizzie's sympathetic attitude about walkers was to kill her.

And then, Carol decided to 'fess up to Tyreese that she was the one who killed his girlfriend, Karen, back at the prison. All this in one episode, and not even the Season 4 finale — one more episode remains before the March 30 season ender.

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To delve further into one of the series' most devastating, but powerful episodes, Yahoo TV talked to star Melissa McBride about the latest crushing choice her character felt she had to make, how deep Lizzie's mental problems ran, how Carol will move on from this latest heartbreak, and how she thinks Carol would interact when, or if, she's reunited with her prison pals.

Overwhelmingly, the fan reaction to what happened in "The Grove," specifically Carol's decision to kill Lizzie, has been positive. The majority of viewers feel it was the right choice, the only choice, Carol could have made.
I'm seeing some of that now, on Twitter. I can't think of what else Carol could have done, you know, putting myself where Carol was … I can't imagine trying to continue moving away from other people, trying to keep [them] safe. So that is kind of comforting to feel like people understand.

There also seems to be an appreciation that this wasn't a gratuitous death, that the story was meant to show that some people just can't survive this apocalyptic world.
Right, and it's sad, this apocalypse, that it would nurture a child like Lizzie in the worst way. It makes you wonder about her childhood pre-apocalypse, or earlier in the apocalypse … what happened, what are the traumas that she suffered early on? Maybe she missed her mother, and that led to this thing with wanting everyone to be a walker, to change, because she's lost people? Don't put them down, because that's, hypothetically, walkers, at least they were upright, and there was some interaction with them? And once you get them in the head, they're gone forever. What's so heartbreaking is that it was through no fault of her own that she was this way.

Go behind the scenes of this week's "Walking Dead" with the cast and producers:

For Lizzie, you think that as long as someone was still moving, like a walker, it meant they weren't gone forever? She didn't see them as other beings, just a different version of people, maybe people she loved?
Right. And this is hypothetical … it could just be that she just finds it intriguing. Maybe she is hearing their voices in her own mind. She thinks it could be even something deeper than that. I don't know. But her storyline made me wonder about her before we met her, what she was going through maybe. She obviously had some sort of issue that was brought into the apocalypse. This only made it worse.

There was obviously some skewed hard-wiring that already existed. The apocalypse, and perhaps the traumas of this world, just made it even worse, and her perspective got even more out of balance.

Again, most viewers seem to agree with Carol's decision about Lizzie, but there were a few who wondered why Carol and Tyreese didn't pack up with Judith and simply leave Lizzie alone at the house in the grove. Why wouldn't that have been a good choice?
I think that would have been horrible. Carol did the best she could figure out, the best she knew how. And she said what Lizzie's mother said. It was obviously something that was comforting to the children, that things work out the way they're supposed to. And she told [Lizzie] to look at the flowers, something Mika had said early on to her. So it was something that, perhaps, the family knew to say to Lizzie when she's having a meltdown, when she's going on a tirade, tell her to look at flowers, so she was looking at something beautiful.

And they buried her with dignity, and Carol did it with love. I can't imagine anything worse than being just left alone, scared out of your mind. Lizzie was not a horrible, evil person; she was a little girl, who could be loving, but who just didn't understand this world.

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Even after all her loss, and all the things she's been compelled to do in this world, Carol's not angry. She's still hopeful, she's still pushing ahead. How does she manage all this going forward?
I think some of that just comes from her pre-apocalypse survival skills, bringing them into this world. She has had to adapt to a lot of things, accept a lot of things, and moving forward, the good thing is, she knows what she's capable of. That's a good thing, she trusts that aspect of herself.

What propels Carol in the first place is guilt over the loss of her child that she couldn't protect; and guilt over the loss of Lori, who, had Carol not gotten caught up in the tombs, maybe she could have been there for Lori's C-section. All of these losses and self-imposed guilt have really propelled Carol to fight harder and harder and harder to be self-reliant and efficient in this world … I think we're just running that risk of, yes, we change and we adapt, but don't change so much that there's no piece of you left. You've got to hold onto your humanity. It's walking a fine line in that world.

But I think a difficult thing for her moving forward is her approach with children. You have Judith, who is only experiencing the post-apocalypse world … what is that going to make of these children? That's something I like to think about: What was a trauma for a child is just an everyday occurrence for a child of the apocalypse. So now [Carol] is going to have to rethink her approach. There's going to be some internal, "I've got to figure out what I'm doing here."

I think she's finding things to be hopeful in. Hopeful, to find hope [laughing] ... if that makes sense, I think she's hopeful to find hope.

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What was the experience like of working with these two young actresses — Brighton Sharbino and Kyla Kenedy — on this devastating episode? We saw them on "Talking Dead," and they seemed especially smart and very savvy, but it was obviously a very sensitive storyline.
Yes, everyone was very mindful of what was happening, and the feelings the children might have been having. But they were very expressive about their feelings. If there was anything that they were caught up by or uncomfortable with, they would speak up, and other than that, we kept [the set] very light. We kept it as light as we could, and as light as they were willing to be, which was all the time between takes. They would just drop it, let it go, and have fun here and there, and then we went back to shooting. It was a great experience working with them, and it was very sad to see them go. I expect great things from both of them, for sure.

This was also the first episode where you and Chad Coleman worked together so extensively, and you had great chemistry. That was a big surprise given all the tension, at least on Carol's part, before she revealed the truth to him about Karen's death.
It was a great episode to shoot with him. He's just phenomenal, and being that we were so concentrated, there was just the four of us in this episode, was really thrilling for me, because we got to dive so deep. And Chad and I both are very analytical actors. We just turn every stone of every word in the script to see what is meant here, what can we bring to this? We were really enjoying analyzing scene for scene, the feelings, what was going on in the minds of the characters. It was a pretty fun experience working with him. I'm really grateful. I think this was a thrilling episode in every way, the writing … Mike Satrazemis, he's our director of photography, and this was the first episode of the series he directed. For the darkest episode that I can remember, this is probably the most beautiful scene, this beautiful setting of the grove … I'm really lucky to have landed this episode in particular.

[Photos: Check Out More Pics From This Season of 'The Walking Dead']

Tyreese said he forgives Carol, he understands what she did, why she did it, and how she feels about what she did, with Karen and David, and of course, with Lizzie. But he also said he wouldn't forget it. Do they 100 percent trust each other now? Or is this something that could somewhere down the road pop up again between them?
I feel like just the understanding between them brings about so much trust. He had that opportunity [to take revenge against Carol]. If he didn't understand, if there was anything that he didn't understand, he could have done it, but he didn't have it in him to do it. His heart is just so — his heart is amazing. When that confession came, it came at the right time. It came at the only time it could come. I think that he trusts her and she trusts him, because they come from a place of mutual understanding. If you can't trust 100 percent the person you're with, then you've got to trust yourself 100 percent. And I don't know if either one of them are there at this point, trusting themselves.

Tyreese initially didn't want to go to Terminus because he was afraid he couldn't trust other people after what happened to Karen. So it was maybe an indication that he does trust Carol, is willing to trust others, that he agreed to head to Terminus at the end. He feels he has an ally in Carol, if nothing else.
Exactly, and that's the most important thing, that they are one another's allies, because they don't know what they're walking into. They just know they can't stay where they are. They've got to go try, but what they're walking into could be another Woodbury … but at least he's got a formidable ally with him.

Watch a "Walking Dead" promo of Terminus:

When, if, the entire group is reunited, Carol's relationship with Rick is still in need of repair. But so much has happened since he kicked her out of the prison … is it possible that he, too, will have a better understanding, a different perspective, on what Carol did, given his own experiences since their rift?
We'll have to see if, first of all, if they ever do reunite anywhere. But yeah, a lot of things have transpired and transpired very quickly, that could totally change the perspective. They're paralleling one another in great ways, and I think Carol kind of understands that. But who knows? Maybe when he saw her face, or saw her with his baby, even if that were to happen, maybe it wouldn't matter what you've been through. Maybe there'd just be some understanding.

Finally, Carol and Daryl … they've been separated for what seems like forever, because so much has happened to each of them since they were last together. If we do see them reunite, what would Carol's reaction be to seeing her friend again?
I think her initial reaction would be one of great relief and joy that he's even alive. Let's just hope that if they do run into one another again, they're both living.

"The Walking Dead" airs Sundays at 9 p.m. on AMC.