Scott Disick jetted off to NYC with his ex, Kourtney Kardashian, and their three kids this weekend — and he told girlfriend Sofia Richie she wasn't welcome to tag along!

While the family of five films the upcoming season of Keeping up with the Kardashians in the Big Apple, a source close to 21-year-old Richie told Breaking Celebrity News exclusively that the young model is “losing her s**t right now!”

“Sofia thinks that Kourtney is trying to get Scott back now that she is single and she is sure that he is going to dump her,” a friend of the model said. “Scott literally told Sofia that he was going to New York without her and the fact that she was not welcome really set her off.”

As Breaking Celebrity News reported, Richie has good reason to be concerned: Kardashian's sister Kim, 37, recently revealed she would like nothing more than to see Disick and the newly single Kardashian get back together and have more babies.

“Scott cleaned himself up for this trip, shaving himself and getting his haircut in the style Kourtney likes,” the source told Breaking Celebrity News, noting Richie posted skimpy bathing suit photos on Instagram while he was away to show Disick what he was missing.