Was going to stay out of this cause it's still hard, also I didn't read most of the thread but dude I made a thread about this happening to me last year and know what the first response was? A link to other threads people made in the same situation. It happens and you're not alone so trust me when I say it get's better, you will move on.
I know what you're thinking " I loved and trusted her, I know it happens but I never thought she'd do it to me" and again, so did we.
Girls are mental, go on all the time about "finding the right guy" and "where are all the nice guys" and when they find one they **** them about then get upset and start greetin when they lose that person because they don't deserve them.
She doesn't deserve you and you don't deserve her, you're too good for her.
Just try not to let the trust issues you will carry try and hold you back in future relationships like they do me, try and remind yourself they aren't all like that, the good ones are out there somewhere!
Best of luck brother in arms, I've been there so if you need to hook me up in private I'm just a pm away!
EDIT: Importantly stay away from booze, I spent a week drunk after I found out and almost ****ed up my final exams. On top of that I made a total fool of myself and still feel embarrassed. Stay away from drink and keep a cool clean head to figure things out.