People often think my dislike of affairs is only from the betrayed spouse's perspective, but that's not so. Some "faithful" spouses behaviour is so utterly awful and shocking, that they betrayed all the other marriage vows themselves. Fidelity is after all just one of those vows and it's not the most important one IMO. However, lots of people seem to put up with all sorts of horrible behaviour and stay in awful marriages, simply because there has been no infidelity. From my perspective, that's the wrong set of priorities.
In this situation - and what I was trying to get across to you on your other threads OMG was that this affair was a terrible idea because your H's behaviour has been so hideous that he needed to know how unhappy you were and the consequences of that, but having an affair is the ultimate covertly expressed choice and therefore you weren't showing your H the real damage he'd done over the years - and he needed to know that.
You were very vulnerable and it's easy to understand why you were tempted by an affair and kind words, but it's never fair or given what I've said above, even sensible to punish someone without telling him you're doing it and it's certainly not fair to hurt others collaterally in the process, e.g. the OM's wife and her children. I said to you before that this is about owning your choices, not expressing them passively and silently and hurting others who have done you no harm.
What puzzles me about your NPD diagnosis with the OM and your hatred of him now is that it was you who pushed this from a friendship into affair territory, as I recall. You were the one who started flirting and pushing for this to be more than an online friendship which as I recall had progressed perfectly normally and happily for a year or so beforehand. If the OM had been a narcissistic opportunist and a serial adulterer, I would have thought he would have made the first move and tried to have an affair much sooner. I remember on your original thread thinking that this bloke wasn't particularly angling for an affair and wouldn't have taken the responsibility for starting one, but that when you made your agenda clear, he possibly said "why not?" and found that he was enjoying a fairly safe but thrilling adventure, after being married for years.
There could be all sorts of reasons why he pulled back from this relationship with you, but you seem to discount the most obvious ones, which is that he felt that this was becoming too threatening and too emotional and he realised this was likely to damage his marriage, so he pulled back. Or that his wife found out, of course.
You invested a lot in him because you shared your secrets with him and it sounds at the very least that he has been unkind in the way he stopped this friendship, but really it wasn't his place to rescue you - his first loyalty should have been to his wife and family.
This brings me to one of the other reasons affairs are a very bad choice - you have found that you have become very damaged by it - not just because you believe you have been treated cruelly by yet another man, but because you feel that you have lost the moral high ground. Just as your affair was disastrous because the brief happiness stopped you from making the most sensible choice to get out of this marriage, there's a real risk that your guilt will prove to be the same barrier.
Don't let it. Forgive yourself as far as your H is concerned - he broke his marriage vows years ago.
Concentrate on making this the catalyst for more important change. Get that counselling urgently, please.