Forgiveness is an essential aspect of a Christian’s faith. We have received forgiveness and are expected, nay commanded by the LORD to forgive all who hurt us. This is regardless of them asking for forgiveness.
Secondly, forget it and move on with life. If not, it weighs you down, and renders you ineffective and useless. It is not worth it because life if too short and precious.
Kumara Krupa Bachala