I agree with RatRolyPoly "I wouldn't answer any questions that you feel degrade you, and the very sexual ones do sound that way. What's done is done and you have to move on from it, but you can't drag him with you if he won't come."
You can decide what you think, OP that your dh needs to know. If he needs to know more that you cannot remember or choose not to reveal, then I think he should accept this and move on.
For the record whether the person having the affair was male or female, this would be my position. Say as much details as you wish to say/an remember, and then your partner has a choice to forgive and move on, or not. But 7 years is a long time to have this hanging over you. If your dh is not happy, he can move on, and so can you.
Tatiana "I've accepted it as my own fault and we're still together." It's great if you can forgive him and move on but I cannot see how it can be your fault he had sex with someone else.
TheNaze "He's obviously besotted with you, to even consider it." That's a nice idea but I am not sure it is true. He certanly is not acting like someone besotted, IMHO.
SandyY2K "I have a suspicion that you won't tell him, because it's sexual stuff you've never done with him or refused to do with him."
If that were the case (and I personally doubt it from what the OP has said) then telling him would be quite unhelpful. It would make him feel he was missing out and if the OP had not done those things with her DH after so many years why would she feel the need to start now, as a sort of penance for having a five week affair many years ago. I would guess that would be awful for the OP and would drive a massive wedge between them.
OP I would personally get some counselling for yourself. I think your husband sounds really unpleasant and hard to live with. In your shoes I'd give him a choice, get over the affair and start treating me like a normal person or let's just divorce and get it over with. It feels to me like he is using the affair as a stick to beat you with. Life is too short.
Lots of projection on here about what the OP may or may not have done. OP I think you need to start thinking of yourself. Please only stay if you want to. You do not owe him anything.