He used her for sex and like she talks about him all the time and stuff and should I just dump her or what

And she can't decied what she wants or who she wants

Dump her man.. whats the joy of being with someone you love when they're thinking of someone else? And its messed up that she speaks so openly about him in front of you? Don't you feel stupid when she does that? Nah... id never put up with that, if your going to be in a relationship with someone its not right to so hung up on someone else, it won't work.

If she can't get over her ex, she is not ready for a relationship. How much time passed between her ex and your relationship?

I would not want to be with someone who brings up their ex all the time.