Adultery: Fling with a co worker

[Law200]

re: Adultery: Fling with a co worker

It is not illegal; but if the affair is over the empoyer is not likely to do much at this point.

I have a question, a family member is getting divorced and around 3 or 4 years ago she had a fling with a co worker. She told her husband, he forgave her and they went to counseling. Now he has left her and is threating to go to her employer and tell the employer about her affair. My question is can he do this? or is there some legal way to keep him from going to her employer about this?