My wife cheated a year before the wedding by having a confusing relationship with someone she barely knew.?

To start off, we got engaged and all was well and overly happy as normal. I have been dating this woman for 8 years straight, without a break, sense she was 15 years old and I was 16 years old. We have had little problems in the early years other than me being a little controlling because I was older. There was rumor going around in high school that I slept with someone while away on a school trip; it was true however I denied it our entire relationship untill we got engaged. I have been completely faithful to her the entire relationship except for that one time. We have been very together the whole 8 years being almost unseparatable. It was a great relationship to both me and her (in both of our eyes). I had the opertunity to go off and live away for a semester of college; however, we didn't take a break and I came home every weekend to hang with her. I made friends with people, but nothing lasting. She was an amazing woman to everyone around her, and liked by all. Once she exited high school, she went off to college to the same college which was in town where we grew up and currently lived. I have never had any doubts about her being permiscuous or sneaky. It was always me that was up for investigation. So things started to get very adult very quick through college and we found ourselves looking to take the next step. Once I got my degree she continued to go to school for another year and a half. Once we got engaged she started to get very controlling and demanding. It was pretty pushy, but I was ok with it because I loved her and was committed to her. I talked about her snapiness with the preist before we got married, and he laughed and told me "she can't be that bad?" and told her about it and laughed. She is a sweet girl and would do anything for anyone like I have said before. So there was some changes in her that started to take place from that point on. We started to drink on a regular bases (Like 2 times a week). We started going out to local bars with other couples. We started to be friends with a wilder couple while having other clean cut couples to hang with too. My wife, fiancee at the time, started to want to be ually adventurous which was fun to me at the time; however, her with me started to become less satisfying to her which I have never seen occur before. We hung with the wilder couple a good bit and started to get naked with them which she has never done before (nothing hands on, just hot tub stuff) About 2 or 3 months after that she started to talk to someone from school. I started working alot, and we purchased a house which we renovated ourselves. She talked to him on the phone for 2 months or so, and then she met up with him (out of town where he lived) while shopping for our new house. I caught her on the phone with him once, and she said that she has been being stalked by him ect. I told her that she can't be nice to this guy, and I yelled and got mad ect. That was the last time that I heard about him. Her friends kinda made jokes about this guy bugging her at school and they joked to her about him being her stalker. He was super nasty and unattractive not to mention he was like 4 foot nothing. Her friends said that she always made him seem like he was aggrivating. The week of the wedding and after the wedding she was super depressed. She told me it was because she was so overwhelmed by everything as she has been being for months. So after our huge honeymoon and stress subsided, I started to be super concerned with how she was acting because it didnt stop; she couldn't get anything done and very indecisive. So I investigated the situation and come to find out she talked to him everyday compulsivly for months up untill two or three days before the wedding, and she also had slept with him 4 of the 6 times that she meet up with him, and she even told him that she loved him. It is the weirdest situation for me, I don't know where to look and what to believe. She argues that there has never been anything like that before that has happened. I told her I don't believe anything and that we need space; however our anxieties are sooooooo high right now, we cannot go about our nights apart. She has had unprotected with him for seconds before she stopped him; however, it did occur (who knows the real truth). We have been to about 5 different doctors, and they are telling me she is bipolar. Even after all this craziness has went down, I still feel like there are hidden lies, and that she is just someone that will lie and manipulate to get her way.. someone please help me... I can't figure anything out!!!!!!!! She had the hardest trouble telling me the truth about everything even making up lies to make herself seem less guilty. Once again, all this started once we got engaged, nothing has been crazy before that point. A simple young loving relationship. HELP!