I agree with Darklady. Jason has threatened, manipulated Elizabeth at every turn to let him have his own way(letting him move into Collinwood, and hot-headed Willie too, giving Jason a PR job for Collins Enterprises) and she has given in to EVERY demand he has made that he had no reason to believe that she'd ever stop. What I am surprised is that it never occured to Jason that someone else like maybe Carolyn might take the most drastic steps to stop him.
Burke dug up dirt on Jason but that failed, however Carolyn intended to murder the man. A possibility like his own murder is one Jason should have considered at some point. No matter how confident he was over his hold on Elizabeth, he knows that no one at Collinwood likes him, especially Carolyn.
I think Burke said that he realized he never really wanted to see Elizabeth destroyed at all, despite all evidence we saw to the contrary during the first year of the show. Change of actors aside, I believed Burke when he said that and that he always had a deep respect for Elizabeth despite their differences.
Carolyn just heard her mother confessing to killing her father. Her reaction was natural under the circumstances. I think if any one of us had been in her shoes, we'd have been shocked too.