Forgiveness is not the relaxing of a boundary; if anything, forgiveness builds and strengthens healthy boundaries. Forgiveness is letting go, which is something you need to do for yourself.
Anger begets anger. Self-pity can turn into despair. When these emotions become dominant, they take over valuable real estate within you that could be used to channel your awesomeness, creativity and talents.
Forgiveness is a commitment to a process of change. Healthy change is a necessity to a happy life and a happy life is your right. Forgive yourself and live.