Scott Disick has "really screwed up" again

A source said: "[He] started talking about being the father he was supposed to be ...

"[But] it was like he undid all his progress from the past week and then some. He really screwed up, again, and the entire family knows all about it."

And the 36-year-old beauty - who has Mason, five, Penelope, three and Reign, seven months, with Scott - is trying to "figure out" life without him after nine years together.

The insider added to PEOPLE magazine: "For the first time, she's taking a hard look at what her new reality could look like.

"Before, she just assumed nothing would really change, but now there's a strong possibility of life without him and that's a scary thought for her. She's figuring it out and taking it as it comes."

Meanwhile, Kourtney and Scott recently met up to talk about how best to split the children's time.

A source said of the meeting: "Kourtney met up with Scott to discuss the custody situation. She wanted him to know that she was going to go after full custody of their children and that she would allow him visitation rights as long as he is sober during the entire time he spends with the kids. For the time being, he is also required to be accompanied by a third party."