Every hurtful memory creates a void, therefore we remember painful and hurtful memories for longer than the happy memories, moreover, we've been conditioned to not forgiving and releasing pain, I have heard a lot of quotes like forgive but do not forget, if you want to hold onto pain, then why even make the effort of forgiving? The society and the rules they have made are very distorted, creating distorted us!
But we always have a choice, every minute of our life, we can choose to be either happy or unhappy, we can choose to love or hate, we can choose to love or hate, we can choose to forgive or release anger and hatered and release ourself therefore.
To forgive someone is to release a prisioner and discovering that the prisioner was you. -lewis B smedes.