To forgive is very important for one’s self. You are forgiving to make yourself happy and free your mind. To tell the person that made you angry you cannot be ruled by stupidity. Not forgiving is like proving that you are a fool, telling the person that you can control me, you can make me do things I don’t want to do.
And sometimes the person that made you angry might be going through a lot which in the first instance, you were not intended to be made angry.