I can’t believe how much every one here has coddled OP.
What exactly was her big lie that you can’t get over? That she said someone wasn’t hitting on her even when he was? Can you fucking blame her? Look at your post again. You are reeking of insecurity, are probably constantly wondering who’s hitting on her, how they measure up to you, what her past boyfriends were like… that would be annoying as shit. Saying “suchandsuch is hitting on me” would just invite daily conversations for a month about that topic, whether you’re good enough for her, etc… all that crap that you SHOULD know intrinsically and not need to have verbally reinforced on a consistent basis. Can you blame her for wanting to avoid that?
Let’s look at this objectively:
-During break up, she said not to bring anyone over… as far as I see, she did not say “no sleeping with anyone”, just don’t do it at the house. She didn’t create a double standard or violate any rule by hooking up elsewhere.
-Since you’ve gotten back together, you consistently go through her phone/facebook/email. You snoop and spy on her to make sure she’s being faithful and to know everything she’s up to. You’re insecure and probably need constant validation from her that you are good enough for her (biggest turnoff imagineable). This has been going on for over a year, probably is very draining for her as she’s receiving zero privacy or trust. On top of that you are constantly making her feel guilty about something she did in the past… RIGHT or WRONG, no one likes that and it will make her resent you.
-The ONLY legit issue - she boned some guy without protection, then boned you without protection, without getting tested in between. This is really the only thing you have a right to be mad about. You have to decide, RIGHT NOW, whether you can get over this or whether you can’t. If you can’t, you need to move on. Neither you nor her will be happy if you spend the rest of your life bringing up past problems, making the both of you feel shitty and guilty day in and day out, snooping/spying, wondering what she’s up to, asking her where she’s been and who she’s with, etc.
You have every right to be pissed at that incident… but if you can’t ever get over being pissed, there is no reason to date her. It sounds in your posts like you can not get past it, better off starting with a clean slate with someone else. There are lots of decent girls out there.
(don’t do the insecure thing again though. Assume that if a girl’s with you, she has her reasons… needing validation is the quickest way to get someone to be sick of you and actually start seeing it your way.)