Being bound to him, we will have to meet him again in some future life to balance the karmic Manifestation Wizard books. However, if we forgive him for whatever the act, then we let him go and release ourselves from having to be involved with him in some future time.
We can then be free to keep climbing spiritually instead of being weighted down by the attachment we created by not letting go, i.e., not forgiving. Therefore, forgiveness progresses from being a nice philosophy to a law of life. In a nutshell, forgiveness frees us. By not forgiving, we remain attached to the perpetrator, enslaved energetically by the relationship and thereby deny our own spiritual freedom.
Frankly, is it not true that if we do not forgive those who do us harm, then we become like them? Were this to happen, who would be in control, they or us? By not responding negatively to a negative act, we keep ourselves from being controlled by an outside force. If we do not react negatively to negative attacks but remain centered within ourselves, we remain in control, in charge of who and what we are. By this action of self-control, we plant virtuous, not poisonous, seeds. Thus, we cannot become engulfed by the poison we sowed, as Saint Dariya declares.