The co-workers may start gossping.. OW won't like that at all...
But, it may end up getting your H fired... Exposing a workplace affair in the workplace is a delicate topic... It depends on the politics there really...
If your H tells you he wants to explore his options :
I refuse to be your safety net while you comparison shop
Don't tell HIM to divorce you, I would just insist that he leave the home, THIS will expose it anyhow, people will want to know why he left...
Are you going to family therapy? Set an adult example by finding a good FT and going yourself.. You can't expect HIM to educate himself about how to repair a marriage if he doens't see you leading a good example