In 2012's "Revelations", J.R. to an unconscious and critically ill Bobby:
J.R.: Come on, wake up, you hear me? Wake up and you get better. And you keep fighting. You keep fighting me! Now I'm gonna tell you something you never heard me say before: I love you Bobby, and I don't know who I'd be without you.
Bobby breaking down and crying after J.R.'s funeral.
Just J.R.'s funeral in general.
Pambecca miscarrying her twins. Cliff's move of ordering the explosion on the rig, even after finding out she was on there, definitely means he's crossed the Moral Event Horizon
Six words: "I shot your father, John Ross."
This, for John Ross, after Sue Ellen wrongly suspects him of sleeping with his secretary Candice, and later lashes out at him ,while drunk, no less.
John Ross: I AM NOT MY FATHER!!! You're so hellbent on punishing J.R. for his sins that you're willing to destroy the relationship you have with your own son? Dammit, I need you, Mom, and you sided with them! I'm your son! Don't you remember that? [...] You're so busy seeing the ghost of J.R. in me that you cannot stop to take a hard look in the damn mirror.