That's not necessarily an easy thing to do. In time all of that completely melted and was gone. So instead, consider envisioning peaceful thoughts for the person in your mind, even if that may seem impossible or totally absurd. But remember, you're doing this for yourself, not the other person. Keep at it each day, and eventually you may find that your pain and anger have softened a bit, and perhaps even disappears in time.
Some people go jogging, some hammer nails, some pound on a punching bag.
Personally, I go play my piano for the physical release, and I listen to music. The other understanding I've learned in the process of forgiveness is that it seems to come and go in waves, especially for the deeper wounds. Then I begin again on the forgiveness journey. I'm not starting from the beginning, however, as I've already traveled a great distance. So once you've forgiven someone, you may find that you'll feel anger and hurt again.