I'm currently separating from my DH with children the same age, for reasons that on paper are much less 'worthy' than yours. We met at 24, I'm in my 40s now and feel like a totally different person.
I'm just not happy and haven't been, on and off, for 5 or 6 years. I think I settled for him in a way because I just found it easier than breaking up with him when I first had doubts, I had counselling recently and that brought up that I tend to people please to keep the peace, mainly due to my dad and his temper... Never hit us or my mum, but anger, control, emotionally distant... We spent most of our childhood walking on eggshells around him. Still do. Sounds very like your husband... Its affected all my relationships with men, I see that now.
DHs parents had screaming arguments, his dad would leave everything up to his mum to do and was silent, uncommunicative... DH is very similar, he won't talk about emotions, left me to cope with everything.
Our parents definitely influence our relationships for better or worse.
All of that definitely affected me and even though my DH is the calmest and most placid man generally, I certainly settled because I knew that to end things (lots of shared friends, lived together in a shared house, etc etc) was going to upset everyone.
Now 2 children and 18 years later, I don't regret the years, the children, the things we achieved, but I do sometimes wish this had come to a head earlier and I'd considered leaving with more insight into it then, because its not as difficult as I thought it would be. Yes he's devastated, but it won't last forever. Yes the children will be upset, but he will see them often, they will hopefully have a more engaged and happier parent who drinks less and can meet someone wonderful who loves him and them. The money side of things and the house are all difficult but will be OK.
When I realised those things, the relief I felt was massive. Telling him was horrible, I assumed he'd get nasty as he's got a bit of a ruthless streak, but he admitted too he'd not been happy for years either and the sex I was putting myself through to keep him happy wasn't really something he always wanted either.
Thing is all the reasons didn't seem enough. We were still having sex, to the outside world we have the best life, beautiful house, healthy children, money... But it wasn't enough. I met someone who I used as an escape from it all and who showed me that it didn't have yo be lie this... I am trying to put it right now by leaving and doing it as calmly as possible.
I guess in my blethering way I'm trying to say people leave for lesser reasons. It's hard, but we are taking it one step at a time and coping ok.