KUWTK : Scott Disick Claims Ex Sofia Richie Asked Him to 'Choose' Between Her and Kourtney Kardashian

Keeping Up with the Kardashians is back for its 20th and final season — and it looks like the family drama ahead won't disappoint.

During Thursday's season premiere, Scott Disick discussed his split from then-girlfriend Sofia Richie. The star claimed to Kim and Khloé Kardashian that Sofia gave him an "ultimatum" at the end of their relationship, asking him to choose between her and Kourtney Kardashian, his ex and mother of his three children.

Previously, Scott, 37, explained that he and Sofia, 22, had taken a break because she felt like he wasn't prioritizing her. They reunited but then eventually decided to go their separate ways.

"I thought I would give it a try and make her more of a priority, but then even when doing that, I feel like she just started wanting to push Kourtney out," he told Kim and Khloé on KUWTK. "And I said like, that's the most important thing to me is my kids and that's my family, and the only family I have, including you guys along with it."

"She was like, 'I don't want to share you as a boyfriend with Kourtney,'" he continued. "And then she literally said with an ultimatum: 'You have to choose me or Kourtney.'"

Tommaso Boddi/Getty; Presley Ann/Getty; Jeff Schear/Getty

RELATED: Scott Disick Opens Up to Kourtney Kardashian About Split from Sofia Richie in KUWTK Sneak Peek

"And I was like, 'But Kourtney is Kourtney and my kids — it's a unit,'" Scott said. "I was like, 'How could you even want that for me?' It just became like, an impossible relationship to keep carrying on with, right?"

In a confessional, Scott added that he would never cut ties with Kourtney, 41, or his kids: sons Mason, 11, and Reign, 6, and 8-year-old daughter Penelope.

"I'm never going to give up my relationship with Kourtney and the co-parenting we have, nothing in a million years, will be worth what we have," he said. "And I truthfully believe if the right person were to even come along into Kourtney's life, or my life, us having children and having this amazing relationship would only be a plus to the outsider."

"Sometimes it's time just to cut the cord," Kim, 40, advised him.

"Yeah, like, I need to be with somebody that I trust with all my heart," he replied. "I trust Kourtney with my life."

David Becker/WireImage Scott Disick and Kourtney Kardashian

RELATED: KUWTK: Scott Disick Tells Ex Kourtney Kardashian He's Ready to Marry Her 'Right Now' in Sneak Peek

Earlier, Kim and Khloé discussed Scott's situation with Sofia while sitting poolside with mom Kris Jenner and her boyfriend, Corey Gamble.

"I think it's got to be a lot for somebody her age to be dating Scott," said Kris, 65. "He's got three kids, the drama of Kourtney, and over time, that would be hard to handle. I've thought about that. That would be hard for me. Most women wouldn't put up with stuff like that."

"Scott, I think is doing the best he can trying to be this amazing hands on father but probably feels like she's sort of like, fighting for the attention from Kourtney and I'm sure that's really really hard for Sophia," said Khloé, 36.

"If I was in Sofia's shoes, I would be like, this is absolutely not normal," Kim added. "I wouldn't want to be with someone that was like, vacationing with their ex."

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RELATED: Kris Jenner Breaks Down in Tears While Discussing the End of KUWTK: 'It's Hard'

Elsewhere in the episode, Khloé opened up about her fertility struggles while trying to have a second child with Tristan Thompson. (At the time of filming, Khloé and Tristan, 30, were not dating but have since got back together.)

For more on the Kardashians, listen below to the episode of PEOPLE Every Day.

"I have been thinking about wanting another kid for quite some time now, and I already have a headstart on that, I started the process a couple months ago when I froze my eggs," Khloé said.

"Tristan and I are not together romantically, so we will not be conceiving the natural way," she added of the NBA player, with whom she shares 3-year-old daughter True. "But he's an incredible father. He loves his daughter and son so, so much and for the past year, and some change I have seen so much growth and so much change in Tristan, which I'm so grateful for. So I'm thrilled that Tristan is on board with turning some of my frozen eggs into embryos."

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Unfortunately, however, Khloé's frozen eggs did not survive the thawing process.

"Eggs are really, really delicate," she explained. "So when you freeze them, and then you have to thaw them, there is a high chance that not all of them will make the thawing out process. I knew that going into this, but I did think that a handful of them would have survived and then we would be able to mix them with sperm. But for some reason, none of mine were strong enough to handle the thawing process."

"So now I have to start the whole egg retrieval process all over again," she said, before going on to tell Kim that next time, the doctors hope to retrieve her eggs and mix them with Tristan's sperm immediately, so as not to have to freeze them.

Jerritt Clark/Getty Images

RELATED: Khloé Kardashian Considers Surrogacy, Reveals She Would Have 'High-Risk' Pregnancy: 'It's Scary'

"I do know that ultimately, there's no guarantees with the IVF process, but I really want to do this," Khloé said. "It's incredibly overwhelming, knowing what all these hormones do to your body, the procedures, the injections, the waiting, the no guarantees, the surgery, the aftermath of it all. It's daunting. It's scary. It's stressful. It's hard."

The surgery "went really well" with 12 total eggs retrieved, Khloé later revealed, but her doctor later told her that she was "concerned" about her ability to carry another child.

"She just said that I would be like, a high-risk carrier for a pregnancy," she told Kim. "I'm not going to get into specifics on camera, but they said like, it's an 80-something percent chance that I will miscarry. I almost miscarried with True at the beginning, but I didn't know that was like, a lingering thing."

"She said she would be afraid if my embryos are so hard to create, she would feel terrible putting one in without warning me that most likely I wouldn't be able to carry," Khloé added, as Kim chimed in by sharing that she had the "best experience" with surrogacy with her three younger children.

Tristan Thompson/Instagram Khloe Kardashian and Tristan Thompson with True

RELATED: Khloé Kardashian 'Finds It Hard to Be Patient' Trying for Baby No. 2 with Tristan Thompson: Source

"This is all really kind of shocking to me," Khloé added in a confessional. "All I'm trying to do is bring more love into my life and into my family. And I seem to be running into more and more roadblocks and it's really hard for me to digest."

By the end of the episode, the Good American mogul seemed more optimistic about her future family plans, telling Kim that after the surgery she ended up with "three healthy embryos" — one girl and two boys.

"I'm so excited," she said. "These three have lasted the five-day mark, which means they are healthy enough to go get tested for any abnormalities, and hopefully they will all be healthy and perfect to move forward with a pregnancy."

"I know that there's no guarantee that any of these embryos will be healthy enough, but I have never even got this far before so I'm so, so excited and grateful," Khloé added. "I'm still not sure about the surrogacy part, but I have time to think about everything and I am just thrilled that I have the potential to grow my family and have more love in my life."

Keeping Up with the Kardashians airs Thursdays (8 p.m. ET) on E!