Kourtney Kardashian is on the outs with Kim Kardashian—literally. 

In fact, she's been purposefully excluded from a group chat with Kim and their friends, the SKIMS mogul revealed during their heated fight on The Kardashians' season four premiere Sept. 28.

"All of your friends call us complaining, whether you think they're the ones going to you, they're all coming to us on the side, saying the opposite to us, so we're all confused," Kim told Kourtney over the phone. "And we're on a group chat that's actually labeled 'Not Kourtney.'"

She said the family made the group because they "have to funnel what your friends are saying to us and have to figure why you're such a different person and why you have this vendetta out." 

Kourtney—who is expecting a baby boy with husband Travis Barker—asked why she would want to be a part of such a chat, prompting Kim to respond, "They're your friends, the ones that you speak to on a daily basis. But you take it all out on me. And I'm trying the best that I can."

The Lemme founder, who has been in a longstanding feud with her younger sister over Kim partnering with Dolce and Gabbana on a fashion show just a few months after Kourtney was styled by the Italian label at her Positano wedding last year, reiterated belief that Kim is selfish.

"It's about you. You are a narcissist," Kourtney hit back. "Anything you do, it's about you and about how it looks to the world about you."

After Kim asked if Kourtney was happy in life, the Poosh founder noted, "Yes. Not when I'm on the phone with you. I was five minutes ago."

However, Kim pushed back, expressing, "We all are concerned. We all think that you're just really not happy."

That struck a nerve, prompting Kourtney to call out Kim's hypocrisy over the secret group chat. "So, you're telling me that I'm unhappy and that I'm miserable and that you have a side chat called 'Not Kourtney,' but you're telling me that you're happy for me?" she said. "I have a happy life and the happiness comes when I get the f--k away from you guys—specifically you."

Kim asked what she could do to make Kourtney feel better, to which the eldest Kardashian sister clapped back, "Certainly not having side chats specifically as me as the topic, like who the f--k has time? Maybe you guys need to go think about if you're not happy. That's what you have time for, to sit and have side chats specifically to talk about me?"

The SKKN founder said she and their friends are "allowed to express concern," adding, "We have side chats about everybody. That's just what you do."

Not Kourtney, though. As she responded, "Then get a f--king life. I don't have side chats about anyone."

She has since expressed doubt that her friends were really involved in the group chat, writing in an Instagram comment Sept. 28 that her friends are "ride or dies." 

Kourtney added, "i believe it was just my sisters from the surveys I've been taking."

Read more details on her explosive fight with Kim here.