You do not need to remain this man's friend. Forgiveness is the exact opposite of vengeance. Vengeance acts in the form of re-acting against an original trespassing, whereby far from putting an endtothe consequences of the first misdeed, everybodyremains bound to the process, permitting the chain reaction contained in every action to take its unhindered course. Forgiving, in other words, is the only reaction which does not merely react but acts anew and unexpectedly, unconditioned by the act which provoked it, therefore freeing from the consequences both the one who forgives and the one who is forgiven. It is within your power to set yourself free.
Forgiveness is the condition of possibility of creating something new.