I can't get past this in our relationship?

when my girlfriend and i started dating she was still very close friends with a man at work with whom she had been in an affair with. she didn't tell me this until he moved away. they were not ually active during our relationship, but they were a few months before, and during my relationship with her he asked her for more. i have had to convince her that it was not respectful to me to lead me to believe he was something other than what he was. she would talk about him often, and even said to me once that she loves him so much, that he's like a brother to him. i feel like any apology has been intricately requested for (she has heavy rules as to how i'm allowed to show my grief). my dilemma is that i can't seem to shake this. i don't know how to get what the unsolicited compion i want from her. i don't know if i'm wrong. i feel like i've been manipulated, but i worry that i'm just a raging hurtful maniac; which is not my normal temperament. i would never dare to avoid resolving these feelings if i caused them in someone else at all. should i just leave her? i'm 29 and she's 25. we've dated a year.