Kourtney Kardashian & Scott Disick Kourtney Kardashian & Scott Disick

The saga of Scott Disick and Kourtney Kardashian takes on another layer of sadness during this Sunday's Keeping Up with the Kardashians. In the clip below, courtesy E! News, Kardashian tells Kris Jenner about how Disick's addiction and selfish behavior damaged his relationship with their kids and made him persona non grata at the Kardashian home.

In the clip, Disick goes to Jenner's house to talk about his relationship with her daughter. He tells her about how Kardashian revoked his "open-door policy" to see their three children by removing the front-gate access codes from his cars so he can't get into the house. Jenner says she feels like she's "missing a piece of the story" and calls her daughter on speakerphone.

"I'm just wondering from your perspective, because Scott seems a little confused because he thought there was an open door policy that he could come by whenever," she says.

Kourtney Kardashian and Scott Disick split

"There was," Kardashian responds. "There was, but that has changed. He was flaking too often, every time I tried to have him sit and have dinner with them he sits in the other room on his phone. He flaked on going to the kid's first day of school, he says 'I can't go because I hate school s--t, I get anxious.' When really he went out and partied through the next day, just like a real f---ing ass----."

During this exchange, Jenner cries and Disick looks uncomfortable. "His main concern is himself, not the kids and that's what's important here is the kids," Kardashian adds.

The couple broke up this summer over Disick's alcohol abuse and apparent infidelity. He went to rehab, but left last week before completing the program, and is reportedly back together with Kardashian.

Scott Disick checks into rehab for alcohol addiction

Watch the clip below:

See more when the episode airs Sunday at 9/8c on E!