Yes, marrying her.
JR was one of those people who is brilliantly clever in certain ways, predatorily instinctive. But he's ultimately self-destructive, emotionally stupid, so he winds up savaging -- sometimes gleefully -- the person closest to him. He can only lose in the long run, and he's probably even resigned to that fate.
JR could want but he couldn't love. His control issues were just too pronounced.
But Sue Ellen was too hard to sympathize with, quite despicable in her own right. Just as selfish, and always able to fall back on her nasty husband to excuse her own behavior.
Which made the show Biblical in a way, very Old Testament.
And screw the idea that JR & Sue Ellen were "good parents." That's utterly ridiculous.