The confrontation came about when Kim approached her older sister about an incident that Kourtney had with Kim's nanny, about something the unnamed employee had allegedly said to Kourtney's youngest son, Reign.
"She said that she felt so degraded by you and you just started yelling at her, and you said, 'Keep your voice down!'" Kim recounted to her sister.
"Oh my god. She's lying," Kourtney fired back.
While Kim agreed that her nanny shouldn't have called Reign a liar, as Kourtney claimed, she said she wasn't going to fire her over the incident.
"If you think she works for you, that's totally fine," Kourtney replied. "She would never work for me with the way she acts. That's totally your choice... She will not ever be around my kids."
Then Kim pulled out the big punches, telling her sister, "Kourtney, you can't even keep a nanny."
"Kim, shut the f**k up, honestly," Kourtney said, before storming away. "The way you're talking is wild."
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While tensions seemed high in the moment, things were resolved quickly. After Kourtney had an emotional conversation with Khloe about the fight, all three of the sisters agreed that they wanted to work on their confrontation style, and the patterns of negativity they feel affect everyone in their family.
"I think that I could have handled it better, and I feel guilty that I contributed to this negativity," Kim told the cameras as she approached Kourtney to apologize.
"I think just as a family, we should work on that," her sister agreed. "I'm happy that Kim came over to talk...I think most of the fights that we have lately, especially the ones with me and Kim, would not get nearly as far if we just learned to communicate without all this negativity."
Later on, Kourtney, Khloe and Scott Disick came up with a family competition to work toward their goal, setting up a "negativity jar" competition, where they each have to put money in a jar when they're being, as Khloe says, "a f**king a**hole"
"I think we all need to be aware of how we talk, and we should want to change this behavior," she added, as the family set to work on the game, aiming to be the person with the least money in the jar by the end of their vacation rental, thereby winning the whole pot. We'll see how it goes!
The final season of Keeping Up With the Kardashians airs Thursdays at 8 p.m. ET on E! See more in the video below.