Beaglebabe - another vote for asking him to leave, I'm afraid. My H said himself that this was the turning point for him - where he could no longer indulge his idea of somehow not losing his family but also managing to keep contact with her and all the desperate adoring emails from her going that gave him a high. He was a romantic idiot too, who'd told himself he'd met the love of his life to justify a very out of character affair. We had one of the strongest marriages of any of our friends before this, but she had previous form, flirted with him for 3 years and eventually, at a big turning point in our lives, he decided to reciprocate.
Anyway, after two or three weeks of him coming and going but still emailing her (he was realising finally that she'd created a character for him that was his ideal woman - same likes and interests - but it was a pack of lies so his excuse was that he wanted the truth. Of course she lied her arse off to cover for it, and inflated the 'I'll love you forever, I've never met anyone like you' lines hoping he wouldn't notice) I told him I'd had enough, I was moving on because he clearly wouldn't, and that I'd be seeing a solicitor regarding money and setting access in stone. Then I put all his stuff in bin bags, drove it to his mate's house (where he was living on a very uncomfy sofa in a damp cottage, ha ha) and went home and rearranged all the furniture so the house was mine. It does make you feel you are taking power back, (and you are), but also gives them the most enormous wake-up call. Seeing his children for two hours a day was awful for him, and I made a policy that I wouldn't even come to the door when he dropped off or collected them. Cutting myself off from him and his nonsense gave me space to think of what I wanted and needed if I was to move forward with him, and a taste of life without him, which wasn't as bad as my initial shock would have me believe.
Another point - at this stage you still cannot trust what he is saying. He is a liar, and has been proved as selfish as they come. Now is his chance to win you back with actions as well as words, not believe he is the great man with two women fighting over him. He can go to hell, or claim his dodgy prize! The fact he hasn't run to her suggests reality is peeping into his bubble and he is realising she is godawful. You will not be bereft forever if he goes - you will recover. In fact, moving on with him is the harder path, and it will get harder still if things continue as they are. He needs to either look for another job or tell management they can't work together for the sake of his marriage. Also, I'd suggest at least telling close family or a few trusted friends so he has to face up to what he has done in public. That will take the illicit thrill out of it all very quickly.
As for recovery - the worst part of recovering is coming to terms (I do not do forgiveness - I never will forgive it) with their behaviour towards you both during and after the affair is discovered. After things settle down and the threat goes away, you will realise this and that is when things get really, really hard. What he is doing now, mooning around and declaring love for her not you is unforgivable and memories of this will intrude on your future happiness for a long time, so consider asking him to leave so you do not have more to contend with at a later date. Take care of yourself x