What should I do??? Love is killing me.?

After the four months we were talking we sarted to date.We've been dating two months now.So my friend moved close to my girlfriend and they started hanging out.My girlfriend told me that he was telling her that I was cheating on her with other girls and he could prove it.So he called her over his house and told her the girl won't answer her phone and he said if I can prove it will you have with me and she said yes.The day after that she said he d her but two months later my friend moved and then he called me crying told me she let him.So I believed her.Later she asked me to quit smoking cigarettes and i told her I did.Then she broke up with me and I went to a party and had a cig and a beer and some one took a picture of me with it and she saw it.She left me today and she told my other friend she really had did have with that other guy and she could never swear on her gpa because it still counts as if your d.What should I do I really want to be her but does sheloveme