Hi sideswiped. I am so sorry you are here. I have been there, my friend, the phone glued to H's hip, the denials, the "she understands...she cares" crap about OW. H finally confessed to me about his A, but it wasn't until later on in the summer I realized just how *attached* they were. Its all devastating.
I am going to throw out some advice. Things that might help you...
1) For now, don't contact OW. Don't go near her. She probably won't care (knows he is married, does this stop her? NO). You won't get any satisfaction from it. You want to appear strong and confident around her and H. Even if you aren't!! You can always confront her at another time. Tuck it in your pocket for now.
2) No need to confront H. You have proof, he knows you know. He is lying to you and will probably lie even more if you confront him. He isn't contacting you, which might only change if you change yourself. He is expecting begging and crying when he contacts you, so he avoids it. Appear strong, put together, and confident when you sees you.
3) Next time you have a moment with H, tell him that you love him, still care about him, and want him happy. But you cannot sit back and watch him have an affair. Tell him that for now, he is free to do what he wants, that you don't condone it, but you realize you cannot control it. Tell him that he is welcome to visit his daughter anytime. That's sad he doesn't see her more than a couple hours a week. Then, after that talk, no more relationship talk. If he spews things at you (justifying his A), then just nod and agree, telling him you are sorry he feels that way. Defending yourself (which all of us want to do!) won't do any good at this point.
4) No more asking about OW or his crazy life that he is leading. You have to remove yourself from his mess. You can't help him fix it.
5) Have you read DB/DR? They are great resources. Other good books are Not Just Friends and Love Must Be Tough. Post here, keep us updated, support others (then others will come find your thread and try to help), but don't relationship talk with H. Pick one or two close friends in real life and talk with them. Hold off on telling the world. Some on here suggest you shout it to the world. Everyone's situation is different so you will have to decide what you think will work for you.
