Many people feel that forgiving someone of their wrongdoing is the same as condoning that wrong behavior. This is not the case. Forgiveness is not stating that the other person did something correct or that his or her actions were justified. Forgiveness is you making a decision not to give someone else power to taint the good you have in your life.
I read once that forgiveness is your acceptance of the fact that you can not go into your past and change what occurred. We know that we do not have a time machine to change the past we have lived. We do have the future to decide how we will proceed from here. We can decide to proceed with resentment or with forgiveness. It is our choice.