Has anybody seen a picture of him? I’d bet he’s “guilty” too (that is, ugly).
That said, if this guy was looking at child porn, she should have called the police. It’s hard for wives to do that, but I have known some cases where they have done so. And it’s less messy than stabbing him.
It’ll take the cops half-an-hour to review his computer history, then review the sites. My humble guess is that she will be taken into court and charged with murder at the end. Pretty bad way to go for the guy.