Deb, it sounds like he is going through withdrawal. STOP ASKING ABOUT OW!
Right now he sounds like he is feeling down, dejected, like he lost a friend (which we all know is actually the feeling she gave him, even though he thinks it was her.)
You constantly asking him if it's really over this time is only making him miss her more and reminding him of her and constantly making his pain resurface.
Let him go into his cave to heal, let him get through his pain in his own way. Goodness, woman, he's recommitted to you. If you keep digging at that wound, how long before he decides he can't take the bleeding and go back to her to stop it?
You have a chance for success, let it heal in it's own time and it's own way, and be there for him. Accept him for who he is and what he says, or else he will just think "why not go back to her? Deb doesn't believe my words anyway, it's damned if I do and damned if I don't anyway."
I know it stinks. My H lied to me and now I am forcing myself to believe his words. Well, so far, he hasn't let me down and has been more open and honest with me than he has in over a year. BUT IT TOOK TIME. Up until just a few weeks ago, he was telling me the globe in the livingroom was not from OW, even though I knew it was. Little by little, as I am calm and accepting and understanding and BELIEVE in him, he comes out and tells me the truth.
Think about it. What would you advise me to do? Think it through, and then do it yourself. You can advise others but when it comes to yourself, you fall apart. You know the DB principles, woman, now live by them. If I were to constantly ask my H "are you thinking of her? Are you really back? Are you really not seeing her anymore?" What would you tell me? What would my H be doing? Thinking about her (because I keep reminding him) and possibly going back to her.
