As you saw, rather than merely accusing him of something that he either would not or could not remember, I tried to appeal to his experience as a child that was not only characterized by physical abuse, but also neglect. This worked. It helped him to be less defensive and open up.
It also helped me because I truly understood something at that point. He would never allow himself to see himself as someone who would do to a child what was done to him. If he were to believe that, then he would not wish anyone else to speak with him again. That was my "AH-HA!" moment.
At that moment, I was able to let go of the hope that he would acknowledge what happened. I knew if he did he would not be able to live with himself. It was for his own psychological protection. At that moment, I was able to better see him as a human being and not a parent, a person who hurt me in the past, or even a pitiful soul. I just saw him as a person who struggles on this planet the same way I do. I was able to have both sympathy and empathy for him. In many ways, this was my redemption.
But as you see, everything isn't fixed in one meeting. Life goes on and problems still arise. And, even though I cannot forget those things that happened in the past, I can let go of much of the emotional hold it has had on me. Some can say this journey is about forgiveness, but too many misunderstand that word to mean an absolving someone of their sins. I don't have the power (or authority) to do that. Rather, I think a better word is acceptance.