I don't know if she was using you or not.

What I do know, is that she's being a bad friend, and you deserve better. I'm sorry her sudden disinterest hurt you. (that would hurt most ppl!) Try to find a way to take care of yourself and not overly focus on her. It sounds like you are cutting her out of your life? Good call. At the same time, maybe there's a reason for her behavior. You could ask before you decide to cut her out. Up to you.

Edit: I think my response was clouded by my own memories of a very bad friend no longer in my life. I agree with the other posters that you need to examine this more closely, ask her if you can. Like seesaw said, this kind of thing can happen when ppl move away. It may be cut n dry, it may not be.

Do you have other friends and things going on in your life besides your cousin? If not, it would help you to have a more fulfilling life.