It's a tough decision, Hope. I did expose my wife and OM's affair to their employer (they worked at the same place), and although it put a bunch of heat on them, neither one of them lost their job over it. I would definitely do it again, tho, as the employer had the right to know that this was going on on his premises.
One other thing I did about OM once, since I used to go in and work out at this same gym where he works. Even though I never confronted him directly (and DEFINITELY would advise NOT to), I didn't want him thinking that I was just doing NOTHING. So I walked right past him, stopped, looked him square in the eyes, and just . . . .WINKED. Smiled and winked at him.
Really unnerved him!!!
My dad is a loud man, but his brother (my uncle) used to instill even more fear into his kids after they'd done something really wrong by just STAYING SILENT ALL DAY LONG. Sometimes even TWO days. My cousins used to HATE it, as they were just WAITING for the punishment to come.
Maybe you can use these two thoughts to come up with something where the OW can think you're not thru with her yet, by any means.