For me, letting go of past hurts (mostly childhood stuff) has required a lot of 12 step work and a lot of prayer and working the 11th step (trying to develop and maintain a relationship with God, and then trying to learn and do His will each day).
I grew up with a drunk, bitter mother and a father who was more threatening and physical toward the children than he was protective of them (from our mother).
My mother died bitter and my father died angry.
I wish them well, but I'm better off without them.
There is no kind way to put it.
I just keep working the steps and working with God to slowly but surely let go of these matters.
And i ask for help, like you did in originating this thread.
I'm glad you did, and i hope all of the responses help.
They have helped me.