When I was involved with my chronic cheater (12 years of other women and heartache), I would take him back over and over, convinced that I could "let go" of the resentment. When he was back, I dissected everything he said, I looked through his things, I made awful snide remarks that let him know just how hurt I was, among other behaviors. Looking back, I see now that I should have done one of two things. Either let him go, or be able to really - and I mean REALLY - clean the slate and not hold a grudge. The latter proved impossible for me, and I never really helped our situation in the long run. I know his cheating was the major "sin" but my attitude was the minor one, and a contributor to many of our problems. Holding him still and pounding him emotionally was not the healthy way to handle the problem. Trust, to me today, is as vitally important as love. I can love you always, but if I can't TRUST you - somehow that is worse today. Unfortunately, our hurt feelings can really fester in there, even if our partner has changed, made amends, etc.
Best of luck