My boyfriend just did the same to me, two years ago I caught him with some "busty babes" apps on his phone and told him how I felt about them. A week ago I found out he was allowing and encouraging his friend to send him dirty text pictures of women and yes it is betrayal and I'm not sure I will stay with my boyfriend knowing this. What you proved (like him) is that you are more than willing to go behind her back and that destroys trust. You have to just keep working on it, though I will say even to me it sounds as if after a year she has maybe settled into a habit of punishing you instead of still being angry about it