Letting Go Of The Past, Yet Needing To Remember It

It is a bit like forgiving, but not really forgetting. You know, sometimes, one of the worst things you can do for somebody is show them unconditional love. Really. I never thought that way before because unconditional love seemed so divine.
Yet some people will take that love and use it as a license to continue to do wrong, yet they still expect the same loving treatment. I see this now, some of my children, the same ones that hate me and think I am a bad man, have been trained in this way. No matter what you do for them or give them, you are still stingy and bad.
My ex used to rant and rave for hours, belittling everyone and cursing them to the depths of despair. She would tell them things such as "you should never have been born, you worthless piece of shit!" over and over and over again, night after night.
Sure, I can find it inside to forgive her, because I have cultivated this virtue and fear not to forgive. Yet I cannot and should not forget. The consequences of this type of verbal and physical abuse will take a lifetime to work out for the children.
I think about the things she said and did to me everyday. It has been 5 years since I divorced her, yet I'm sure these thoughts cross my mind daily. How do you think it is for the children?
For the most part, they seem to recognize that she has some problems, but generally, they choose to forget the past. Once in a while it comes out, but usually they want to love her and have a real mother so badly that they just ignore the past. That's probably a good thing!
This relationship of an abused child and the abusive mother is strange. One moment they are like battling enemies, the next they want her to hold their head on her lap.