Aidandylan,

My A lasted 3 months or so.

WOW.. I know this is more than just irony... I did the exact same things as your H. I literally felt like I was on an emotional roller coaster. Here is his delima.. he has to hurt someone. He has already hurt you. now he's faced with hurting another.. the guilt is eating him up, and the OW is laying it on thick.
Also, If our similarities continue... he is starting to feel vulnerable. He dosn't really want the OW. He thought he did, and has said and done some things that have put him in a corner so to speak. You need to reinforce to him that "We can work through this."
but ultimatly he has a difficult task ahead. I'd like to be able to talk to him. It sounds like he's dealing with, or will deal with the same things I have.

Mike.