Here is a quick synopsis of my predicament. I have been going out with this girl for over 3 years. After about a year of dating, while she was in school there was this guy that she was friends with that she admitted to me that she found very attractive, but they were just friends. I didn't think anything of it till I snooped in her email and found out she was debating with her friends whether she should sleep with him or not. I am 100% sure that nothing ever happened becuase I intervened at the time. She apologized and said it was just fantasy, blah, blah blah. Fast forward to today, I have just put a $3,000 deposit on an engagement ring the is going to cost me around $7,000 and we are supposed to be moving in together soon. I still have snooped occasionally because I was always slightly paranoid, but I got the feeling that she was totally past all that. This morning I checked out her AOL chat archive and found an IM between her and that guy from school, who is engaged and getting married soon. Basically the conversation started off innocently, but then she said they should meet up as friends. He said that would be hard and he would want more. She said she didn't know about that becuase he is engaged, but that they should have gotten together before he got engaged. Now, he only got engaged a few months ago, so this meeting would have been when my girlfriend and I were going out. They left it as they weren't going to hang out for now, but they should start talking more over her email (which I can't check).
What does everyone think about this. I truly thought we were in love and I was ready to take the next step. Now I don't think I could ever trust her again. I hate being this paranoid the whole time I am with her and I hate invading her privacy, but it is necessary for my piece of mind. Do you think I should launch her? Also, do you think that I should tell this other guy's fiance about what has been going on?
Sorry it is so long, I need help