Girlfriend CHEATED on Me, Please help , I DONT know what to do, This is killing me?

[marcus]

My girlfriend and i have been dating for around 4 months. This girl is honestly obbsessed with me in everyway and mind. She always tells me "not to cheat on her" and we both talk and think about each other nonstop. just a few weeks ago while she was drunk, she confessed to sleeping with another guy but she was a party and really drunk and so was the other dude. She did it during when we had one of our little fights over something stupid, but it was not why she did it.

Ive seen posts on twittter about this two going back and forth saying they love each other, but she wrote that he loved him while she was drunk and at that party, he writes it all the time. when she was drunk that night and told me i told that this wasnt going to work out, its over. and she just broke down into serious tears, she calls me almost everday crying and apologizing and wondering why she did it. she explains to me that she had no control for what she did, but i dont know if i can beleive that. this girl did not have the best life growing up, loss of her parents (drugs) she has fallen in love with me and she says im her everything. she makes posts on fb and twitter saying "what have i done? ... "who am I?" ..."I wish i could go back to the way things were".. but what really upsets me is that she told me a month later

.******.I saw her before she told me and after she had done what she had done, we we went to the movies and i saw her phone and she got texts from the boy who she did it with and she has not reponded to one of them after that night*******

What do i do, Please, i need everyones advice.

Much appreciation