Relationship delima. Please tk time to read!?

Okay, here is whats going on. I met this girl about 2 weeks ago, i met her through my cousin. And she said she liked me, so neither one of said we went out officially, until after i herd she kissed someone else. I talked to her about it, and she said honestly she did. But know that we go out iam the only person she would ever kiss again. And now for some strange reason my cousin and her arnt friends no more. so my cousin is telling me how she is a b**ch and all this, but im wondering if she is saying those things about her because she is mad at her, or are they the truth, what do you think community.