I don’t think recording someone having sex without consent is justified regardless of how that individual has emotionally harmed you.

I thought this was a settled view - that abuse isn’t justified. You can’t hit someone because they hurt your feelings, you can’t rape someone because they refused a date, you can’t record someone without consent because they cheated on you. Those are separate actions.

If he had controlled himself and only recorded them kissing or otherwise showing the cheating without the sex, he wouldn’t have been punished by the courts at all. Only she would have been punished.