I feel for you so much as you live with such incredible stress and the sensation of walking on eggshells. It's a truly horrible state to be in, wreaking havoc on your self-esteem, imagination and nervous system.
I'm wondering if anyone's ever led you to make sense of the affair, why it happened. If you can't make sense of it, then I don't believe it's possible to help your husband make sense of it. I suppose you could say it just appears senseless.
I'm a big believer when it comes to us having many different aspects to who we are. Sometimes, parts of us will kind of 'wake up' without us realising. I know I sound a little insane but there are times where I'll be basically left to wonder 'Okay, which part of me is at play now, which part of me am I 'channeling', in a way?'. Is it 'the lazy Netflix watcher' or 'the highly energetic' sense of self or perhaps 'the emotional eater'? When it comes to parts of our self that suddenly 'wake up'...I'm typically a passive easygoing sort of gal but if someone was to threaten one of my kids, the part of me that would wake up would be 'the lioness' or 'the incredibly fearless super bi*ch' who would literally fight someone to the death if circumstances were life threatening. This leads me to wonder what part of you maybe 'woke up', which led to the affair
Could it have been the part of you that was longing for far more excitement, the part that wanted to experience high levels of chemistry through sex, the part that just couldn't suppress such wonder, wondering what it would be like? Was the marriage not strong enough to ground you out of wondering? Was there just not enough energy in the marriage to fuel or satisfy your energy levels at the time? No need to answer, just leading you to wonder.
I've found, there can be a constructive sense of wonder and imagination and a destructive sense of wonder and imagination. Not a lot of people talk about the intensity and significance of wonder and imagination. They're aspects of us that can either drive us or destroy us in a number of ways. Sounds a little strange perhaps but I find if I'm not careful with how I'm managing that channel or those channels (wonder and imagination), they can get out of control. Managing how to open them and close them remains important. When a channel of wonder opens it can be incredibly energising, leading us to do things we wouldn't normally do. When it suddenly closes, we can be left thinking 'What the hell have I just done?!'