Though they're on better terms these days, a few months ago Kourtney Kardashian and Scott Disick had ugly spats over his excessive drinking.

On Sunday's episode of Kourtney and Khloe Take Miami, the new mom, 31, gives him an ultimatum: Stop drinking or get out of 7-month-old son Mason's life.

"You're not going to be around Mason while you're working on yourself," she tells him (see video, above). "There's not even a 1 percent chance ... I can't do this anymore. I love Mason more than I love you. And that's what it is."

Disick, 27, pleads, "I'm telling you I'm gonna fix my life. I'm not going to lose you and my son."

The full episode of Kourtney and Khloe Take Miami airs Sunday at 10 p.m./ET on E!.