I do feel for you - its not great either way really is it. If he isn't hiding anything (which i suspect he is) then it is equally as bad because he is keeping things from you for what reason? its none of your business? nice
. For me, it wouldnt be about knowing the exact amounts, i doubt there is the need for that as you seem to be in financially secure, in fact it would hardly be worthy of conversation for me, beyond "oh yes, i got X amount of £££ for that particular contract/stint of overtime/whatever" "oh, ok then, nice one, where shall we go the weekend?" But HE has turned it into an issue by being secretive about it - why can you find your joint account statements but not his, bills etc, but no bank account details - he is deliberately hiding it from you, its not even a case of him being patronising an saying "oh, its extra money so i didn't think it was relevant" etc, he is taking steps to prevent you knowing about it.
For me there would be only one way out of this where i would want to continue with this marriage and that would be if he was in financial difficulties and he was desperately trying to sort it out without telling you. Even then, he absolutely should have told you and not tried to hide it, but i can sort of understand why he might want to hide that (of course it would depend on the origin of the difficulties - gambling etc = bad, a business venture gone belly up - how can i help?). Him keeping the money back for himself is a deal breaker, he is working longer hours so that he can have this money, it sounds like his family are secondary to this - nup, not for me.
You sound incredibly strong OP, you may have some difficult times ahead, maybe when he realises you are serious he might open up about things, but it may well be too late by then, he is a foolish man indeed. You are going to be fine.