It isn't that you need to bring up the image of the person and say “I forgive you” or “I love you” or “I forgive myself” because this is still just interacting with your private mental constructions of a “me” and an “other.”
But rather the recognition that must arise for true release, to feel the energy of true "forgiveness", is that the person or situation being resented (etc.) as well as the sense of self holding the resentment (etc.) are total constructions of the mind. All of this “i can't believe s/he did that to me” exists solely in thought form, and it's appearing so far in front of you.
The moment attention recedes or pulls back from the stirring of such thoughts, the whole story dissolves. There is no one to hold a grievance toward and there is no one to have felt wronged.
All such notions are constructed and projected out by the appearing thought forms. It's never anything else. It's always JUST a thought form being paid attention to.
So the play of resentment and forgiveness...this too is a play of thoughts in the mind.
:::peace & release