the problem is that she was LITERALLY acting on those feelings. The thing here is to find out if her facebook fantasy is on her friends list and if so, get a divorce by way of cheating wife. I would probably kick her out of my bed and make her sleep on the couch if not in a hotel at that point. If she was wanting some she should have went to the husband, not a facebook photo.

How is that cheating? Just fantasizing about someone isn't cheating, it's what's keeping her from actually cheating on her husband. And sometimes people need to spend some times with themselves. In my opinion, have a talk, but don't divorce or anything. At most tell her that you think it's inappropriate and that you feel uncomfortable with the situation. With any luck, she'll stop. If not, then start thinking about a divorce.