Feeling saddened and upset and used.?

I feel extremely betrayed by my best friend, Last weekend we went out and her cousin joined us (we used to work together but i quit and he has a gf) and that night we made out without though. I didnt give him my number bcuz i felt bad for his gf and the next day my 'friend' was telling me how he was leaving his gf and that he had moved out which i believed but then today i checked her messages and nothing supposily she erased them and also the calls. I told her i didnt believe her so she called him and he never mentioned or asked about me, which makes me think she made the whole thing up like she did once more a while back with someone else. I feel betrayed and lied to, I actually thought her cousin and I could have something but I feel so stupid bcuz i was the only one thinking about that. Am I right by feeling betrayed and not want to talk to either of them?