Does he likes her?!?!?

I like this guy and we talked about us getting together sometime, but then he just started acting like it didn't hapen, and he is dating this girl that is a total skank and she is just nasty, he knows how I feel and idk if he does it on purpose but it seems like he makes a point of flirting with her in front of me and then flirting with me when she isn't around.... it makes me so mad, its like do you think that all the flirting that you do with me is going to make me forget that you rub it in my face about you two? I asked him why he was flirting with me if her was dating her and he said because he was only dating her to get a piece of a**.... So I was like, well that means that that is all tat you want from me too and he said that wasn't true that he had a "real connection" with me, idk what to do!!! please help