i don’t know what to do………

So i feel like such a bad friend!!!!  I have this friend who has been my friend for years, however during our friendship we have also gone back and forth into being more then friends, and every single time he screwed it up by not knowing what he wanted or another girl.  Recently we took a break from each other and didn’t talk for about 4 months.  After that 4 months he convinced me that he had changed and i was what he wanted.  That lasted all of a week before he decided to go back to his ex gf.  I don’t hate him for it because what he did different this time was he was honest with me and i never hate anyone when they are honest with me.  So we decided to stay friends, because we have a great friendship when we are friends. 

Now my dilemma is that this weekend i’m throwing a birthday for my cousins who are twins, who he happens to be friends with as well, i actually met him through them.  I asked him not to come this weekend because it was only a few days ago that this happened between us and if he comes then she will be there too and i don’t know how i would feel about seeing them together.  I’m actually not that upset that he went back to her, but i feel like it would upset me to see them together.

Now i know thats selfish and not fair but i have put a lot of time and money into this night and i want to have a good time too.  So i don’t know what to do because i feel like such a bad friend by asking him not to come. 🙁  But i know if he comes i will have a horrible night.  sigh…………………………………..