One reason we resist forgiving is that we don't really understand what forgiveness is or how it works. We think we do, but we don't.
Most of us assume that if we forgive our offenders, they are let off the hook — scot-free — and get to go about their merry ways while we unfairly suffer from their actions. We also may think that we have to be friendly with them again, or go back to the old relationship. While God commands us to forgive others, he never told us to keep trusting those who violated our trust or even to like being around those who hurt us.
The first step to understanding forgiveness is learning what it is and isn't. The next step is giving yourself permission to forgive and forget, letting go of the bitterness while remembering very clearly your rights to healthy boundaries.