Damn dude, it sucks to go through shit like that...
Since you brought up an ex story, I have one as well...
I started dating this girl when I was 17, it was my first really serious relationship, I was young and stupid just like every other 17 year old kid. After about 6 months of dating, driving 30 miles 3 or 4 times a week, and a month before my 18th birthday, I start getting a wierd feeling and she comes up with some common excuses as to why we weren't seeing eachother as much as the months before... 'she can't drive to my house because she has to save the miles she puts on her new car..' 'she can only go out of town once a week and she wants to do it with her friends "once in a while"... not just always drive to my house'... So on my birthday, I go to her house and she makes me breakfast, I still feel wierd but try my best not to show it. She had the day planned out at Disneyland, I had never been there before. We get there and after a few hours she picks up on my distance and asks me whats wrong. I tell her I've been feeling strange about our relationship and the way she'd been acting. Then she says she has something to tell me, but wanted to wait till after my birthday, which instantly made it clear it was bad. I couldn't enjoy the day from that point on, after a couple more hours I demand she tells me. We sit down and she tells me she was at a party, she did cocaine and she made out with a guy... I felt crushed. So we left and on the way to the parking lot, she asked me "...do you even want to talk about any of this...? and I said "...there's nothing to talk about" and we didn't say a word to eachother the whole ride home (2 hours), she 'pretended' to sleep, I think she did anyway, to make it less awkward... We get to her house, she gets out and I drive to my house, another 30 miles....
...That night, I tell my friend from school online about everything and he says "what did she tell you?" so I said she told me she made out with a guy... after that he got really pissed off and said "dude, fuck that, she's lying to you! She did a lot more than that, she told me last week everything that happened, and that she felt guilty and had to tell someone! (he told me the details, from when she told him (which I was sure at the time wouldn't have been the complete truth as she must have known he would tell me, being a much more loyal friend to me than her) He said she told him they pretty much got to everything before oral sex) --at this point, in my life, looking back on this incident, I really DO believe she went down on the guy, even though I know she would never tell me the truth, even after years of being broken up-- ...
...So after all that, I was more PISSED than anything because she lied to me. My friend said he felt guilty the entire week because he knew and promised her he wouldn't tell me because she said she wanted to but after my birthday, I didn't care about that, I was just glad he told me, it showed me this guy was a real friend. I drive to her house and confront her with the information. She denies it and starts LAUGHING! I get even more pissed and start to leave. She tries explaining herself and I end up leaving anyway...
...In the end I got back together with her and we ended up breaking up in very similar circumstances 6 or 7 months later...
Moral of the story, don't get back together with a chick that lies to your face without thinking twice...
I learned a lot though, so there is some good to come from this experience...
Thanks for making me relive that in such detail, it gave me a wierd feeling...