You are making up scenarios that don't even exist and making yourself nuts over them.
Okay, your wife is pursing this guy. In her head, she is divorced and free to date. bad on her for choosing a guy you both work closely with. That's crappy.
This guys has done nothing you know of! So everything is pretty much irrelevant.
I think I have told you this before. YOU HAVE CHOICES! You can stay in this position as long as you can tolerate being around your W. You have no reason to leave it. You can also chose to leave it. You can choose to say it's because your W is pursuing someone else within the organization and you do not feel comfortable. But to name a guy who you have no evidence on would be wrong of you. You don't have to cover for her. You can say whatever you want to anyone about her. I wouldn't go around ruining other people's lives because your wife is going after them.
It's very obvious you are itching to expose your W. You need to say something to someone. So go ahead. No one is stopping you. Who is it you are hiding this from? Who is it you need to tell so bad? Tell them!
Hey, I exposed my ex up down and all around. I don't regret it. But I can't say it made me feel wonderful. I think I felt worse when I didn't get the reactions form his people I expected.
I just ask you not to bring down this guy who probably is just an innocent bystander in your wife's flirtation. You want to bring down your W, make sure there are no other innocent casualties.
I hope in time that you can just not give a crap about her actions anymore. Who she choses, why she choses them.