Ted should have....

Ted could have reversed the tables on her and said she was a cheating wife who plotted his demise by having an affair and making up stuff about him. And It would have flown. She was having an affair and was pregnant, by a younger man. If she was not having the affair it would have never work anyway. also she was about to pay the blackmail money. She was as bad as he was outside of the murder plot, or was the plot to drive her insane, I still don't know that answer. He could easily prove she was pregnant and had a previous abortion....I am not cynical, but just thought the ending was lame and my plot was a much better fit.