How do you forgive someone that hurt or disappointed you so much in the past?

I’m trying to convince my heart to forget and let go of something that really heart my feelings, but it is like the disappointment and sadness are more powerful than my desire to forget and leave it behind and open a new page with this person.

This person never said sorry, but he does trying to talk with me again while I don’t want to talk with him, I’m just being nice and nothing more than that. Maybe we should talk, but I am not feeling it will erase everything.

How you do that wholeheartedly?