Hi Sivonnah!
If I can add to what AIRAM and MeganB already kindly shared, there is a beautiful forgiveness ritual that @Silverbear made.
And @christina4 shared a lovely Buddhist prayer for forgiveness of all (including the self):
→ Buddhist Prayer for Forgiveness
Wishing you all the best with your forgiveness work. I think it’s a very wholesome and beneficial thing to do 
Much love and many blessings! :spakrles: