He did not know that the moment he stepped out of the hospital, his niece would make a taunting call to his wife. He could guess as much what that girl had told his partner, though he was not privy to its exact content.
As for the series of events that had happened thereafter, he was unable to predict them as well. If he knew that his niece was so adamant on eradicating his wife and was audacious enough to orchestrate such a grand plan right under his nose, he would be equally ruthless, too.
It was easy for him to deal with that rich missy. The bigger headache was his wife confronting him about his relationship with his niece. What could he possibly want with that lass? To him, Song Enya was a relative. She was his niece, and that was all. He had not reached the point where he would throw off his moral compass to hold incestuous thoughts about a relative, really.