Thank you all so much for replying. I haven't told anyone else about the situation apart from a family member and a close friend so it really helps getting different views.
Both the people I've told think I should try and make it work, they say our relationship is too special to give up and they say it was a stupid mistake and they know he loves me. So to read all your views was a bit of a shock, but I know I needed someone to recognize how awful this is without being influenced by their perception of us as couple. To everyone - and including me up until a month ago- we do seem like the happiest, in love couple, which is why this is so surreal.
First of all while I know what he did was awful, not just the cheating but the whole devious orchestration of it, I do think I haven't been fair in my description of his behaviour, in the sense that we have talked about it a lot already and it was in the last few days that he started to shut down. Our counsellor which he sorted out, did tell us to try not to focus on the details if we want to move on - so his view is that he is trying to carry out her advice - he doesn't feel the constant analysis is getting us anywhere. and he has tried to explore the reasons why he cheated in the sessions. so not defending him entirely, but yeah he has demonstrated some remorse in my view.
So I've since told him that I'm not ready to stop analysing it, and I suggested we started writing letters to each other because the conversations were just turning into tears and rows. He agreed and he did explain things in more detail in a letter, more along the lines of how he felt and his attraction to her, how he enjoyed the attention, and how he got an excitement/thrill that reminded him of his bachelor days, which has helped me understand his motives more, though still pretty devastated over the fact that he could be so attracted to someone else, while being 'in love' with me. Is that even possible? it's not for me anyway.
Our counsellor says digging away and looking for more answers isn't going to get me anywhere. I just have to make a decision whether can I cope with what he has done and make a choice to give him the gift of trust again, with the caveat that if he does it again I leave, or.... decide I can't get over it and walk away, make a fresh start.
I suppose what he has done is reason enough for me to leave anyway, so finding out anything else won't necessarily change things. That's her view anyway what does anyone else think about this?
heforgot - that point you make about the answers not necessarily making you feel better is true. Sometime I wish I didn't know what she looked like, or had spoken to her, because in a way I feel like I know her now and she will always be present in our relationship.
I did ask about lie detector tests jjct - great idea - but my counsellor said the results are often inconclusive so she doubted that would help me feel satisfied anyway. I would think the whole process of doing it would be damaging - I don't think I'm there yet but I will def consider it as an option in the future depending on how things go.
NeverAgain2013 - I did ask her after I confronted him, only a few hours, but yeah he could have contacted her and I have thought about that. I do realise she owes me nothing and would probably rather do without the responsibility of breaking up a marriage so I could see why she'd rather help him than me. I don't know, her responses were always quick and seemed genuine, but then I've realised not everyone thinks like me or has the same moral code. so yeah a massive pinch of salt as you say.
To all of you that advise me to run like the wind - Getting to Happy and Chrysalis123 - I know exactly why you're saying that. Made me laugh regarding the hair on fire.
Doing that would take massive courage that I'm not sure I have, I've fantasised about it, but realistically I love him and don't want to give up our lives together, that probably makes me look weak i know.
I haven't definitely decided to stay but I have taken on board what the counsellor said about choosing to let go or not and that being the decision really, going to give myself a few weeks to decide and he knows that.
I think the new dilemma I have is knowing he will be attracted to other woman and could act on it. He's a good looking man and I've seen him be approached in bars and clubs. Temptation will come again. He says he knows that and wants to work on how to control those impulses in counselling. he says the experience has been so traumatic he would never want to go through it again, and realises he took us for granted. Would never do it again etc.
so yeah, still deciding, but finding the counselling helpful, would appreciate your thoughts and will keep you posted. x