help Please

i am a typical male i had a sexual relationship with a so called friend for around 2 years she's still single so am i.She calls herself a "B" which i see at times,selfish one, the trouble is she my sister best friend at the moment  i see her regularly. Now i feel hurt, and angry about the way she treated me from  the first time we met it was only a  one night stand well suppose to be. Bye the way she does not talk to me much if at all, after seeing her ex who  i have met.She shuts up when others are around  or tells my sister boy friend about me.What should i say or get help i am trying to work through this mentally and just move on with life.