Well, I hate to say it but I wouldn't be sure it wasn't a physical relationship. You may never know, but saying "it was just a kiss" is such a cliche it's not even funny. I hate to admit this but when I was young, I once had an affair with a married man. I learned alot from the experience. I won't get into how or why it happened or try to defend myself. I now know that even if I was lured into his trap, it was wrong and I was selfish. The reason I bring this painful memory up is because that is exactly what he said to his wife about our affair. Believe me, it was more than that. For all I know, he will never tell the truth about it. To me, it sounds like the two of them acted a little too guilty for a "peck." Who pecks anyway? Two people who are admittedly attracted to each other and having "an emotional affair"... I find it hard to believe that they'd just have a little peck.
I'm not passing judgment on you, mama. I don't think you need harsh advice or loud instructions right now. I'm sorry if my observations were a little rough as I know you are in a world of hurt. The part that bothers me more than the affair is the way your husband is in general. The narcissism, by your definition. Not being there for you. I mean, I'm sure there are wonderful things about him that you haven't shared with us, but for most people, support is a big one. Even that is something I think many husbands screw up from time to time, but during your most difficult moments ever? That's a dealbreaker for most of us.
So what are you trying to save, exactly, is what I'd want to know more about from you. Because it sounds like it hasn't been so great ever since that really bad 4 year period, and now this. Who knows, this could be the turn around? But it doesn't sound like it based on the way he's acting now, and if he really is a narcissist, all i can say is good luck.
I tend to take alot of blame in my marriage for being non-affectionate or frigid, when in fact it is because I am not getting my own needs met by my husband and he is totally disconnected from me a good deal of the time. But it makes me feel guilty because I think to myself that he will eventually go elsewhere if he's not getting love and affection at home, right? That may be true, but this is not a reflection on me. If he chooses to be a crappy selfish husband and makes it impossible for us to have intimacy, which in turn makes me cold and bored with sex, then he chooses to be a cheater, that all has nothing to do with me. But it takes alot of constant reminding myself and checking my perspective to not fall into that trap! Don't you do it either.
Sounds like you are being wayyyy too soft on him right now. He needs a serious reality check. He's about to lose everything and is in no position to call the shots. It is not about punishing him or him appeasing you, it is about proving that for once he's willing to be an equal partner in the marriage, which you've been doing all along. Since he is the one who has caused this grief, he can either enter into a serious counseling commitment (maybe he can find another therapist?) or move on. Because he doesn't seem to think he needs to change. I would want to separate and then see how he behaved, but that is just me. I would want him to know without any shadow of a doubt that I would not tolerate this kind of betrayal, and that I could definitely do better than that even if it meant being alone. Then I think I would feel a little more in control of the terms of our relationship during such a vulnerable, unsure time. It would give you the space you need to figure out if you really can trust him again and want a future with him, as well as see how serious he is about you. If he is a real narcissist, he will turn into being all about him. How could you do this to me? How could you abandon me like that? ... turn it back around on you as if you are the one who made a huge mess of your marriage.
I wish you the best of luck, sincerely.