Letting go is a higher form of forgiveness; it is taking forgiveness one step further.  Without letting go of the thing you are forgiving calls into question your actually having forgiven.  You cannot release it and hold to it at the same time.  Ponder that.  The grace and mercy of God comes to us as a free gift and it does not keep looking back at our past sins and failures.  “Love keeps no record of being wronged” (1 Corinthians 13:5c NLT).  God is more interested in what we are becoming than what we were.  That becomes our pattern in forgiving a fellow human.