The stupid neither forgive nor forget;
the naïve forgive and forget;
the wise forgive but do not forget.
Thomas Szasz
Forgiving the other person does not mean that you have to allow that person back into your life. It simply means that you are refusing to allow what he did to continue to disrupt your inner peace or to negatively affect you in any way.
Many teachers teach that you should forgive and forget, but I disagree with that. Just like everything else in life, you should learn a lesson from your experience and use it to your advantage. That person taught you something about his character and who he is as a person. If you forgive and forget, you are losing that valuable knowledge. Forgive, but don’t forget.
This does not mean that you revisit the incident frequently or bring it up anytime that person’s name is mentioned. That would not be advantageous to your inner peace. Put it out of your mind completely, but keep that information filed away in case you ever need it to prevent yourself from being hurt or taken advantage of by this person again in the future.