Life is short. Too short. I realize it may sound like "worldly" philosophy to say that, but it is true. Even from a Christian standpoint, we are exhorted toward what is profitable and good and useful and constructive in this life. We do not want to "waste" our life, as John Piper would say. Thus, Christians and the rest of the world would all agree on this one point: life is too short to punish ourselves for how we feel about bad things that have happened to us. How do we punish ourselves for it? We ruminate, we obsess about it, we agonize and think and think about it, we bitterly dwell on the person who committed such a horrible offense, and we dream about their downfall, as if it does anything to them whatsoever. We hold them in a mini torture chamber in our minds, but behind the illusion of their captivity in our own minds lies the reality of our own self-imposed captivity. And we fret and frantically grasp for some kind of control, which only makes things worse because in no time at all we realize how prone we are to get hurt again, and again, and again.
When our anger or sorrow about an offense gets to the point where we are holding ourselves captive, imprisoning and punishing ourselves with fear, worry, anguish, anger, and bitterness, we have gone beyond grief and into the realm of pointless, needless, useless, fruitless, self-imposed self-destruction. We aren't stopping them from being selfish. We aren't even changing the situation by our endless agonizing and ruminating. We aren't holding them back by holding on. We are holding ourselves back. We are punishing ourselves. We are stopping ourselves. And the world, the offender, and life, moves on without us.
You can't go back and make it go away.
You might not even be able to make it go away now.
But punishing yourself will do nothing.
Life is too short.
Don't waste your short life with this. It is too short to not let go. It doesn't matter how big the offense. It may be something utterly unfair and terrible. But your life is not over. You can acknowledge how unfair it was and feel the pain and grief without punishing yourself over it. The two do not have to go hand-in-hand.