Naturally, the KKW Beauty founder isn't proud of the fact she couldn't sort through their differences in a civil manner... And neither is their mother Kris Jenner, who halted production for seven days after seeing the worrying footage.
"When my mom saw that, a clip of that, she cried. And was like, 'Who are you guys? Like what is going on?' Kourtney and I are obviously fine now, but we shut down production for a week after that. I think everybody was really shook for a minute, and just was like 'this isn't our type of show, what's happening?' We want everyone to be comfortable and safe."
Kim continued: "It's not my proudest moment, but we were going through it, and she's made the decision to take time off now, and I think she really needs it and I think that will be so much better for her."
The matriarch spoke out about the estranged siblings' physical fight after the first trailer for the latest season dropped in February, confirming she was mortified when she watched the footage.
“I wasn’t there when they had that argument. And I have not seen them really fight like that since they were in high school,” the 64-year-old said.
“There was one time, I think it was way back when, when Kim … did anybody see when Kim beat one of the kids over the head with her purse because her rims on her car weren’t right, it was so silly.
"It took me back to that, but it made me really sad. I was like ‘You guys can’t be fighting with each other,'" she added. “That’s ridiculous, you know. Grow up."
During her chat with Ellen, the momager was also asked why Kourtney will feature heavily in this season after despite announcing in December 2019 that she'd quit. At the time, Kourt said she felt immense pressure to share certain parts of her life with the world that she'd prefer to keep private.
"She’s filming again. I gave her some [money],” Kris said with a laugh. “I think she just needed a little bit of a break. You know how we all hit a tipping point, and she hit a wall. She was frustrated and she felt under-appreciated and that her sisters didn’t understand her boundaries. So I think after taking a little bit of time off, she’s seen the light. The Kardashian light."
She continued: "We actually all really enjoy doing the show because we get to be together all day. We’re about to start our 19th season, we’re just filming it. So yeah, I think she would miss us."
Kim was the first to admit we'd see her relationship with her eldest sister go from bad to worse earlier this year.
"What sucks is that season 18 will come out soon and it gets worse before it gets better," she revealed on Ellen DeGeneres' talk show in January.
"If one family member goes on vacation a lot or takes time off a lot, the other family members have to step in and take over those hours," she revealed. "So for the past year, Khloé and I have been taking over her hours, working, because we need content to make the show.
"It's been exhausting for us when she hasn't taken that into consideration without making a decision of what she wants to do,' she said. 'Stay on the show, not, but to be in this limbo and have us do this for so long is frustrating."