There are lots of opinions on confronting. I confronted my husband when I knew he was having an affair and demanded that he stop. It didn't really make him stop, but at least he knew that I was not an idiot who could be easily deceived, and just that made me feel better.
As for whether you should confront OW, you need to decide that based on your relationship with her and your work situation. Generally, I do not believe in bringing family problems into the workplace. But, in this instance they are already there. Only you can make that decision. But since he has already asked you for a divorce, you should be prepared for them not honoring your request to stop the relationship. Your work situation is about to become very difficult. Weigh your options carefully.
In all the time that I have been talking to people about affairs and their marriages, I have come to the conclusion that at this point, the best thing for you to do is to assume that your marriage is over. He's already involved with her to the point of demanding a divorce, and hanging on and fighting for something he doesn't want won't save the marriage. So, assume that you will be getting divorced, do you want to upset the work environment too?
