Solost I will tell you the hard truths, as I see them. They are as follows:
All the time your H was happy to be with you and your life together, he wouldn't have needed to be this manipulative with you. However, the whole point of being manipulative is that other people won't recognise the signs or the motives behind each action. You might not have seen it, perhaps because you were easy-going and accommodating and in general, on important decisions, his will would prevail.
You have said yourself and we can see your strengths here; you are at heart a positive, optimistic person who tends to see the best in people. It is entirely possible that because he tended to get his own way, he didn't need to manipulate you as much personally.
I bet if we spoke to some of his colleagues or bosses though, we would hear a different story. His parents might recall examples of when he evaded personal responsibility for things and let others take the fall.
I also want you to take comfort from the fact that it is fairly typical in longstanding relationships that people make bargains - overlooking a person's faults (within reason) because despite them, that person's love and loyalty is beyond question and consequently their faults don't seem that bad. I'm sure it occurred to you in the past that your H was a bit pompous and stuffy and not the most re-constructed of men when it came to gender politics, but because you believed him at heart to be a good man who adored his family, you could put up with it.
A crisis like this forces someone in your position to look at the man in a new light and recall those bargains, which seemed small-fry at the time, but now add up.
It doesn't mean your life was a lie, because he wouldn't have been as bad then. He was where he wanted to be and he could achieve his aims quite comfortably, without having to manipulate people too much, in his personal life.
However, as soon as he had something to hide and feel ashamed of, those basic traits kicked in with a vengeance. And of course, he is still in that place now, because he isn't truly in the place he wants to be and can't bear being held responsible for this mess.
There is something I really would like you to focus on Solost. Could you have ever described your H as a feminist? Did he really value women, other than in a chivalrous, paternalistic way? Did his views influence yours about career women, or females who asked for what they wanted? Why would he not have forgiven your infidelity?
Can you also see now how he has still been manipulating you and the OW and how every interaction you have described, has him making it all about him? The staged row between you and the OW, the tittle-tattling about her to you, the staged "nervous breakdown", the counter-attacks that you were controlling him, the wheedling manipulation of your daughters to tell him they loved him, the "woe is me" E mail to his friend this week? All these things are all about him starring in his own drama, with no thought or concern for the wreckage he is creating in other people's lives.
Why do you think he can't face his parents? Like I said, although they no doubt love him unconditionally, they can probably think back to traits he had as a child and might even be blaming themselves, poor things. I'm assuming they are getting on in life and their pain at being estranged from their son must be acute, as well as any mis-placed guilt they might feel for what he has become.
It's not that you missed all the signs Solost, it's just that he didn't need to show them so vividly with you then, coupled with you doing what everyone does, cutting him some slack because his good points tended to outweigh the bad.
However, it is terribly important for your own survival that you see him as he now is - and stop thinking of him as a good man who was led astray. You have got to start seeing him as your foe - not your friend, because he will stop at nothing to achieve his own objectives, even at the cost of his DCs, let alone you.
I know that's hard - to change your view of someone after such a long time, but remember that all was well as long as he was getting what he wanted. That doesn't make you foolish at all. But see now that as soon as his objectives were not the same as yours, he was capable of callousness and manipulation to get what he wanted. The OW will find this out in time too of course and if she's got any sense, she will remember that he once treated another woman very badly too.