Should I go to my friends 21st?

Ok I'm been close friend with this girl (NOT GF/BF, just friends) since I was 13, she turning 21 in June.

She didn't come to my 21st after stating that she would the day before. I was pretty angry with her that she dog me like that and we were not on speaking terms for a few months. She eventually told me in January of this year, that she didn't come because I was back friends with someone, that betrayed me and her, a few months before and she didn't approve of me hanging out with him again.

We are now speaking again and again friends, however the last couple of weeks she being very bitchy and act like she doesn't want to be my friend. She barely want to talk to me, at a party she would not associated with me, she will only call me when she want something, when I try and call her or txt her she would not answer but I see her on facebook like 10min via her phone latter talking to everyone else.

I'm getting tired of being treated like crap by her, I tried talking to her that I don't like it and she still does it. What should I do.