Kourtney Kardashian is tired of hearing complaints about beau Scott Disick -- and, on Sunday's Kourtney & Khloe Take Miami, she really loses it when sister Kim accuses her of not keeping Disick, 27, on a tighter leash.

Kourtney, 31, is quick to come to Disick's defense.

"Open your eyes," Kim, 29, tells her in the clip (watch above). "Scott is out, taking shots of tequila 'til 4 in the morning when you're at home changing the diapers! We're on your side. We're trying to support you!"

But Kourtney, 31, doesn't want to hear it.

"Go hang out with Khloe and talk sh-t about Scott, you f--king bitches!" she seethes.

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