In the vast majority of circumstances I'd be confused as to why you'd want to confront the other woman. Your cheating husband is the one that made vows to you, OW owes you nothing. But then I realised she was a friend of yours.
I have had 2 boyfriends cheat on me with close friends. In one case the OW was actually dating another friend group member at the time, the other I found out was cheating when I found them snogging in a cupboard, in my house, at my birthday party! Tbh, once I found out I just froze them both out. They didn't exist to me. Ultimately I walked away from both friendship groups. Not to avoid them, just the whole situation made me realise I needed better friends!
In the first situation no one believed he would cheat (bar the guy OW was seeing, he dumped her), they were good church-going folk, I was the bitch breaking his heart for no reason. I walked without a backward glance, I later found out a few months after that OW got sloppy drunk and told everyone everything, not just the cheating but some other stuff that had been going on too. Did they get ostracised for it? Of course not, he was still precious friend that could do no wrong. Was the catalyst for some others that had already distanced themselves a bit (including OWs ex) walking away permanently. Apparently they're still together, but not publically, and seem somewhat ashamed of their relationship. I saw her once a couple years after and she jumped and tried to hide from me. He begged for me back more than a few times, I usually didn't reply, once or twice replied with laughing faces.
They have to live with it, I'm free. I have much better friends, awesome DH and family I adore more than life itself. I don't regret it, irregardless of how hard it could be at the time.