To forget a wrong is the best revenge. (Dictionary of English Proverbs/Thomas Preston)
It’s important to learn from what happens, especially if someone has wronged you. For your own self-protection, don’t forget the lesson learned. On the other hand, don’t let the anger or hurt control your life, happiness, choices, and future. There is a difference between understanding the wrong and not allowing that person the ability to hurt you again versus keeping yourself in a victim position where all of your time, energy, and resources are consumed with the wrong (feeling sorry for yourself, fanning the flames of anger, and constantly trying to get even). Meanwhile, the person who wronged you moves on with their lives and more or less forgets you even exist.