"If I don't see you at filming, you're completely fine when we're not in this environment," Kourtney claims to her sisters.
"Then actually, you should go," Kim tells Kourtney.
"I don't want to be near your fat a**, OK?" Kourtney shoots back as Kim yells at her to leave.
Kourtney later does a side interview, explaining why she escalated the fight so quickly.
"I don't understand why there's all this judgement about the way that we each want to live our lives. We should be accepted for what we each want to do and it's not a positive environment for me to want to be in every day, when I feel like they're so critical of me," she says. "Every day that I'm coming in, I'm like, why am I choosing to be in this environment? And I think I just, like, reached my point of not being able to tolerate it anymore."
Khloe continues to note that she's confused by Kourtney's behavior, adding, "We know there's been friction recently, but I don't think any of us knew it was this bad and heavy."
Keeping Up With the Kardashians airs Thursdays at 8 p.m. ET on E!