Poet and Psycho-analyst, Merle Molofsky wrote:
There is an important difference between recognizing one's own transgression, atoning, and then forgiving oneself, and forgiving those who have transgressed against oneself, who do not show any sign of repentance or admission of guilt, or who continue to transgress and harm one.
In my experience, when people ask me why I can't let go of a grievance, and of the feelings associated with that grievance, such as resentment or rage, it just doesn't work. It intensifies my feelings of rage, of being misunderstood, of being abandoned when I most need understanding. When people advise me to let something go, it just inflames my anger. Unless we are working with someone as that person's therapist, or perhaps if we are very very close to that person, I don't think we can evaluate and judge whether someone's grief and anger and resentment, if unabated, is dysfunctional. There is much I have let go of, much that I have forgiven, much that I have forgotten. I can't, however, forgive anyone who has done any of my children serious harm.
Forgiveness is very personal. We all have to find our own path toward forgiveness....