Forgiving you is the way I forgive myself and then eventually I experience that in reality I have done nothing that needs forgiveness.
The metaphysical teaching of ACIM is that there is nothing to forgive because nothing happened. Although that is usually not our everyday experience the metaphysical teaching is essential because without it we will believe that there is something real to forgive in the world.
Be willing to forgive the Son of God for what he did not do. T-17.III.1:5
While we believe we are here in this world of separation our way out is forgiving others.
Jesus asks us to forgive him in the Course as well as our brothers.
Forgive me, then, today. And you will know you have forgiven me (Jesus) if you behold your brother in the light of holiness. He cannot be less holy than can I (Jesus), and you can not be holier than he. W-288.2
It is a miraculous perception to know that when I forgive someone else I am really forgiving myself.
I need to forgive myself for making up an image of myself that has attacked my Creator and wants to live a separate life.
I need to forgive myself for making up a Creator who is now an enemy and in competition with me because I project this image of an enemy onto everyone around me.
When I forgive others, I am forgiving myself for making God into an enemy.
And now is God forgiven, for you chose to look upon your brother as a friend. T-30.II.5:4