Disick, 32, moved into the house – which one source close to him tells PEOPLE he originally bought as an investment property to flip – two weeks ago, when his assistants were photographed moving his belongings out of the mansion he shared with Kardashian, 36, and their three children.
"He's in a black hole," the source says. "It's a whole lot of darkness where he's at right now. He's spiraling out of control."
A group of women were spotted entering his home for a bash Thursday.
Splash News Online (2); Inset: Bryan Steffy / Getty
Meanwhile, Kardashian is focused on her family. She's been spending time with kids Mason, 5, Penelope, 3, and Reign, 7 months, along with sisters Kim Kardashian West and Khloé Kardashian while shooting Keeping Up with the Kardashians.
"Kourtney again spent a lot of time with Khloé and Kim. The girls filmed at Hugo's in Agoura Hills," a source said of the reality stars' outing Tuesday. "She seemed happy to be with her sisters."