I will try to say some words of wisdom here, at least kind words. There are no right answers to your dillema. There are probably lots of wrong things you could do. I suppose professional counselors might have good solutions. This is a problem that a lot of people have had to deal with, more so years ago, when it was swept under the rug. After my mother died, her sister, my aunt confided in me that my father had molested her when she was nine years, more than once. And exposed himself at least a couple of times. I know the feeling of disgust you must have had. You have to do what is right for you, years have past, but the knowlege is still there. If I were in your position, I would never have anything to do with your father, but could you possibly arrange to meet with your mom, and occasionaly so your children could meet your mother. Years ago, no one had any social support for such situations, which could be one reason why your mom didn't do anything at the time. If your children ask why for such a strange situation, say there are adult reasons that the situation exists. Someday they should be told the truth and they will understand. I think in the long run, you will be glad that you spent time with your mother. She did nothing wrong other than staying with him, for whatever reason. I am sure she did not condone his behavior. I always struggled with the question of whether to tell my brothers about my father, I decided not to. It all happened 60 y.o. Who knows what he has been up to other times that we did not find out about. It definitely is a sickness. I hope in some way what I say could be of some help to you. We can never choose our relatives, if we could we would never choose such sickoes.