Welcome to Plathville 's Moriah Plath Has Reached a 'Breaking Point' with Olivia: 'I'm Done'

Welcome to Plathville has been two houses divided for a while now — but the rifts between the members of the Plath family appear to be increasing in Tuesday's two-hour episode.

In an exclusive clip from the hit TLC series, Micah and Moriah Plath are extremely frustrated with their sister-in-law Olivia Plath following an apparent "meltdown" at a family gathering to honor the birthday of their brother, Joshua Plath, who died at 17 months old in 2008.

"I feel like Olivia should understand that her feelings are definitely important, but not everything's about her feelings," Micah, 21, says in an interview after the incident. "If there's something that outweighs what you're mad about, you can set what you're mad about aside and go do this one thing. You don't have to talk. You don't have to be friendly or whatever but you can still be a part of what's going on and then work on your garbage later."

That "garbage" likely had to do with Olivia's relationship with her mother-in-law, Kim Plath, 49. They famously argued in the show's first season, leading to Olivia, 24, and her husband, eldest Plath child Ethan, not speaking to Ethan's father, Barry, or Kim for several years. The memorial for Joshua was the first time they'd see each other since Olivia and Ethan moved away to Tampa.

TLC

"Today I have officially reached my breaking point with all of this drama," Moriah, 19, says in an interview. "I am so done. I am so over it. I'm just tired of fragile relationships. If you have to constantly walk on eggshells around somebody's feelings, if you spend three to four years of your life trying to make that person happy and then you make one decision that doesn't make 'em happy and it affects your whole relationship? That's not a true friend. And it hurts to say that but that's the harsh reality I'm waking up to."

Moriah adds, "I love Olivia but if somebody's going to make me choose, I'm going to choose the person who's not making me choose. I'm done choosing."

RELATED: Welcome to Plathville's Ethan Plath Questions Choosing to Do Reality TV: 'What's Done Is Done'

Moriah has been asked to choose between her sister-in-law and best friend Olivia and her mother Kim several times, including in season 3, when she asked her mother not to attend her first concert because Olivia would be playing alongside her.

TLC

In the clip, Ethan, 24, also appears to be irritated by his wife's behavior.

When younger brother Isaac, 16, asks him if Olivia knew that Kim would be attending the memorial, Ethan simply shrugs and mumbles, "I guess. I don't know."

RELATED: Welcome to Plathville's Kim Plath Opens Up About Being Abused by a Babysitter as a Child

TLC

For her part, Olivia seems to recognize the error in her ways at the memorial.

"I know that what I did puts a damper on the whole day because instead of them being able to focus on what they had to focus on, they're thinking about the fact that I had a meltdown in front of all of them, and it's no longer just about Joshua, like it should be," she said in the aftermath.

When a producer asks if she was "so wrapped up in your own feelings that you couldn't think about anybody else," Olivia shakes her head and starts to cry.

"I think I was so wrapped up in what I was experiencing that I didn't have clarity or capacity to think about how much those kids might want or need my support," she replies. "And I feel like I really let them down."

Never miss a story — sign up for PEOPLE's free weekly newsletter to get the biggest news of the week delivered to your inbox every Friday.

The two-hour episode of Welcome to Plathville airs Tuesday at 9 p.m. ET on TLC.