No, Mr. Hacking, your son waited for Lori to go to sleep and went in and stabbed her to death. Then tried to hide evidence and concocted a story.
Completely sane acts. Plain and simple.
We used to say, "cold blooded murder"--wouldn't be at all surprised if he had planned this longer than even what they're saying. If there was any "snapping" at all, I think it was when he realized he was going to get caught.