Justin Bieber, 21, is one cold-hearted snake. At least, that’s how Kourtney Kardashian, 36, feels after he dissed her in a recent interview. Justin joked that Kourtney was just “using him” to get back at Scott Disick, 32, and now she “wants a major explanation and apology.”

“Kourtney wants a major explanation and apology. She’s not the one who leaked their romance to the public. She feels like she’s being punished and it just goes to prove her initial instinct — that Justin is too young and too immature for her. She’s kind of beating herself up for ever getting involved with him in the first place, and not listening to her gut. She really regrets the whole thing,” a source says.

Even worse, Kourtney feels “stabbed in the back. She has been nothing but respectful towards him and their relationship. She has been so protective of him and now she feels completely stabbed in the back,” our source adds.

During a recent Bert Show radio interview, Justin jokingly said, “I’m being used, man. What can I say?!” when asked about his romance with Kourtney. Obviously, it wasn’t the best thing he could have said, so we can understand why Kourtney is so upset. If you ask us, she definitely deserves not only an explanation, but also an apology.