“Create in me a pure heart, O God, and renew a steadfast spirit within me. Do not cast me from your presence or take your Holy Spirit from me. Restore to me the joy of your salvation and grant me a willing spirit, to sustain me.
It can be hard to forgive and let go but it's important to remember that harboring that resentment and holding a grudge can hurt you even more. The word "forgive" really means to give something up for yourself and not for them.
Buddhist Prayer of Forgiveness - If I have harmed anyone in any way, I ask their forgiveness. If anyone has harmed me in any way, I forgive them. And if I am not ready to forgive, I forgive myself for that.