You haven't forgiven and you can't move on.
What does it mean if I can't let go of something negative that happened in my relationship ?
If you truly love your partner, it should overcome whatever negative things may come across your relationship. But it takes some time for most people. Only perfect and pure love can forgive all negativities and move ahead. So.. If you feel about your partner in that manner, focus on the positive things between you and hope for the best.
You shouldn't be in a relationship.