Om Swami
How can I forgive someone in my mind when I can't tell them?
Forgive silently and set the person free
If you have hard feelings toward someone, say in your mind that from this moment you do not hold them responsible and that you are setting them free. Anger is punishing yourself for the mistake of another.
From this moment on I'm not going to hold you responsible for what happened in my life. I'm setting you free. I have no more hard feelings against you.