I'm in the same boat. WH cheated with MOW coworker...she's been to my home, we've shared recipes, I went to her wedding, gave her gifts. It's brutal. And he still works with her. This is a giant problem for me. WH can't immediately leave his job but there is a move and department changes coming up within a year. I told him I'd suck it up until then to see if those changes separate them. We can't survive on my paycheck alone and I have kids and a mortgage to think about.
He went NC with her other than strictly business. She was in agreement as she wants to save her marriage as well. I can't monitor what he does while at work, but I do see his emails and they have proven to be business only. My rules are, as much communication through email as possible, no face to face alone, no IMing, no phone calls. It's impossible to monitor and I already know he's broken some of these rules as they work together in the same department and it's impossible. I told him if he has to break one of these rules for business he needs to tell me...we're struggling with that last part because he'd rather stick a fork in his eye than voluntarily bring up that woman's name to me...but I think he's starting to get it. I also get a copy of his Outlook Calendar for each week, he tells me his breakfast and lunch plans and I can track his phone anytime I want.
It SUCKS and I don't really see ever fully healing while he sees her every day, but for now I have to deal. IC says that even if he got a job somewhere else he could cheat there too, but having her still in our lives is just a daily scrape of the scab, kwim?
I'll be watching this thread for advice too.