WOW, I read your problem and question, my best advice from a female point of vew is that you two need to splin up you. You to will never be able to trust eachother completly. that will onley lead to more hirt feelings, betrayel, and drama.  Im sorry to say this but you to are not helthey for eachother.  

It is true about girls craving attention, but if she went to the extreme to make another guy think she is going to sleep with him to get the attention she is wanting she will go farther whin it comes down to it.  You have every reason not to trust her. I wouldent.  I understand having ishews but that is no reason to leed someone on.  If her hart was truley into you she would have never done that no mater how much she needed the atention.  If she would lead someone else on like that what is stoping her from doing the same to you. Oh and you sayed that she was willind to beleve that you didnt cheat on her so that in return has made you feel like you should bleve her, here is another point of vew the reason she is so willing to beleve you is becouse she has allready cheated on you and is feeling guiltey for it, and she is wanting to hide the fact that she has and is using reverse phicolagy on you. To kinda gult you into beliveng her, and not looking in to the fact that she may have cheated on you to much. eater way it goes your trust has bed broke for eachother, those lines haven ben crosed, and now you to should count it as a loss, and go your seprate wayes. 

I hope that helpes