Thank you, all, for your support and kindness. It means more than you can know. I don't have the words to express my gratitude--not for anything you can say (though that's appreciated too) but for simply reading it and tucking it away to tell others.
At this point I am quite astonished that I wrote and posted it. Every word of it is true; including the parts that expose the sides of my personality that I'm ashamed of--like being retroactively happy that my grandfather suffered in his death. It is true that he caused extreme pain, directly or indirectly, to three generations of descendants; but if you saw the way he died you might feel that he paid his debts. No court of law in the world would sentence someone to die that way.
I had planned to tell the story in an vague, truncated way, but it all came spilling out in a cathartic rush of feeling. I'm shivering now and I wonder if I'll come to regret posting it. I guess if one person can benefit from reading the story, and get out of the org, or pay closer attention to their kids, or think about their own childhoods, it will be worth it.
Someday, hopefully with her permission, I will tell my wife's family story. Some would argue that it is just as bad.