She's pretty good at pretending she's fine, but you know she's got to be mortified!

Kourtney Kardashian is choosing to focus on her kids as baby daddy Scott Disick continues to drink and party with hot models in Miami, and it can't be easy for the reality star to stomach. After all, rumors swirled these past couple of months that the mother-of-three was considering giving The Lord another shot at their relationship, so this is basically a giant slap in the face.

LD joined his former girlfriend and their children on the K clan family trip to Costa Rica last week, but after an alleged blow-up with Kris Jenner and Kim, he took off for a more carefree vacation in the Sunshine State, and it's not going over well with Kourt.

"Kourtney hasn’t been happy with Scott for weeks. It has nothing to do with what he is doing in Miami right now. She just doesn’t like when he parties. He is an irresponsible dad when he parties. Kourtney returned to L.A. on Monday with the kids. She is not happy with Scott. She allowed him to come to Costa Rica for a couple of days so he could have fun with the kids. Scott’s behavior is again getting out of control. He is partying a lot," a source dished to People.

"Kourtney just wants him to make good choices because of their kids. Partying and making out with different girls publicly isn’t exactly the best behavior when you are a dad," the source added.

We have a feeling she's going to aim for another sexy hookup with Justin Bieber, just to prove a point that two can play at this game!