Hi there! I have been out of town and just saw your thread and would first say how sorry I am for you and then would like to say thank God you found this site. It literally saved my life 3 years ago, and while my M is still in the crapper, I have found much love and support here. You are getting that now.
It sounds to me like you are doing everything right. The MOW/coworker my WH had his affair with was a touchy/feely sort who apparently hugs everyone at the drop of a hat. (His excuse for the constant perfume on his clothes.) I was told so many times what a wonderful person she was, under appreciated, abused by her BH. So, I too needed full proof before I could confront the BH. I flat out asked my WH and he kept denying and let's just say followed the playbook by making me feel guilty and like a loser for even suspecting it.
So, point is, you are doing the right thing by getting absolute proof before proceeding. A word though about revealing your sources to the BW. When I first phoned BH, he was totally surprised (thought his marriage was perfect) and asked me for proof. I met him at their condo, while WH and MOW were traveling, and gave him copies of company emails I intercepted via keylogger from our home computer. He asked to make copies, which I obliged, as I knew he needed proof as well.
Well, to my surprise, he laid all these in MOW's lap as soon as they returned and she ran them right into WH's office first thing. My source was busted. I KNOW this is what I had to do, but unfortunately as the BH felt he had to give his wife the opportunity to explain herself, he gave it all to her. Her excuse was that I was crazy and a computer genius who made it all up, including the affair.
Needless to say, WH never used our home computer after that for company email. I did confront him with some proof via FedEx while they were away and told him I had proof, but now he knew how I knew everything.
He came back home to our marriage, probably as MOW refused to leave her $ BH for my WH, but as they work together still, the fantasy lives on. Especially now, as her BH has had enough of her lies and manipulation, he is divorcing her, my life will continue to be hell.
Rambling here I know, but I think, even though you are not worried about your WW losing her job, for your own sanity, insist that she change jobs so that she never have contact with this man again. Even our MC told me that I could never compete with the fantasy of an affair (not that I intended to). As long as your WW can have any contact with this man in any fashion, you are at risk of losing your sanity and never being able to trust or believe her.
Also, just wanted to point out that the BW is probably going to believe her WH; she will WANT to believe that he is not capable of an A and he will do everything to convince her that your WW and you are just crazy. Be very factual with her and try to keep emotion out of your conversation with her as much as possible. She will be devastated, even if she manages to keep in control, and you just never know how she will react. It wouldn't even surprise me to find out that this would not be her WH's first affair; he sounds capable of being a serial cheater due to his work schedule. If you can expose this man and hang him, power to you! If I exposed my WH and MOW to HR, undoubtedly WH would be the one to be fired and it would have been detrimental to our family.
Hang in there; be strong. I still think it is good advice to seek the advice of an attorney just to test the waters. Knowledge is power.
I know you want to R with your wife and I applaud you for that. It is a tough road ahead regardless. Take care; we are here for you.