Well, he/she would never be my friend again. Can not trust him/her.
I would stay away from that person on a personal level. I would more than likely not speak to him/her for a while at first. If we spoke again, it would not be the same ever. How could it be. How could I learn from that experience if I forgive, and forget.
There is something to forgiving, but there is only repeating if you also forget what was done to you.