I think it is very difficult for a marriage to move past an affair.
First, I don't think that you have to answer questions that you find humiliating and degrading. There is a difference between needing to know the truth, and needing to humiliate one's spouse.
I think that its common for someone who has been cheated on but stayed in the relationship to then cheat on their spouse. It's almost like playing both roles helps them make sense of what happened.
It's also common for someone who has been untrustworthy to project their guilt. So it makes sense that your H is both acting like he is cheating, and yet wanting to drag you through the coals over something that happened 7 years ago.
My marriage survived an affair. The conversations that we had between the 2 of us were not productive to moving on, and we spent time in counseling. I think you are on solid moral ground to tell your husband that you will ONLY discuss your affair with a marriage counselor present, that you know you were wrong and made a huge mistake, but that you are not going to be verbally beat up over it. The reason he doesn't want to have these conversations with a counselor is that he knows he'll have to fight fair, own his own shit, and treat you like you have feelings.
For all those on the thread that think the OPer needs to disclose every gory detail, if you were the spouse who were cheated on, why would you refuse to have these conversations with a marriage counselor? Why would you refuse to go to counseling? It is easy to relate to the concerns of the cheated on spouse it is everyone's nightmare but look at what he is refusing to do.