People get into a heavy-duty sin and guilt trip, feeling that if things are going wrong, that means that they did something bad and they are being punished. That's not the idea at all The idea of karma is that you continually get the teachings that you need to open your heart. To the degree that you didn't understand in the past how to stop pretecting your soft spot, how to stop armoring your heart, you're given this gift of teachings in the form of your life, to give you everything you need to open further.
Writen by Pema Chodron to Sage Woman

Before you forgive someone else forgive youself. You are the most important people to forgive before you can truely have the power to forgive the other person. Forgivness comes from with in and without doing to work within yourself you can not truely forgive anyone else. What follows is up to the other person and whether they have forgave themselfs. But at least for the person who forgives themselfs come peace, harmony, love and respect for themselfs for doing the hard work it takes.
Peace, Love and Joy to all.