Surely if her dh was arrested and cautioned she'd have found out
Not necessarily at the time. She would have found out once the court proceedings against this , frankly very stupid and selfish, woman started.
The same applies to this woman's husband. There wasn't a hope in hell she wasn't going to be found guilty and all she has achieved is uninvited publicity for all concerned, including 2 people who were not cheating on their spouses.