I teach on anger and forgiveness on a regular basis. I find forgiveness to be a fascinating subject - something that strikes at the core of what it means to be both human and divine. Anyway, there is a new book called The Faces of Forgiveness by two profs from Bethel University and Seminary. It's pretty deep, but the research facts on forgiveness were interesting.
Stephen Sandage said that there are three key components to forgiveness;
1. Humility; the ability to understand that you are made from the same stuff as the next guy. Because of that, you are capable of doing the same evil to others as has been done to you. This keeps you from overreacting and treating your offender like scum.
2. Empathy; flows out of humility. Because you understand your ability to do wrong, you are able to put yourself in the shoes of your offender. You don't excuse them but you are able to see how they could do what they did.
3. Differentiation; the awareness that you are distinct from others. It's the opposite of being emmeshed or co-dependent. The co-dependent person needs affirmation from people. When they are offended it is very hard for them to forgive because they can't stand alone. Their anger is the only thing that protects them. But the differentiated person can more easily forgive because they find their worth apart from the affirmation of others.
Something to think about.