This is long but I hope it might be useful -
A few years ago I was where you are now, with the slight difference that I kept asking about finances (I'm really good with spreadsheets), but was told the accountant was looking after it - he would lose the plot unreasonably and shout at me that if I insisted I could take over the "whole fucking lot", mortgage, bills etc., and go and earn the money to pay for it all as he was going to stop "carrying this load".
I'd worked in an area with good potential before our children were born (surprises), and as he was away a lot I ended up as a SAHM. My self esteem was very low so I always ended up backing down when he had these meltdowns. He has earned good money and so I worked part-time since the children were small, and got quite involved in community work rather than looking for a full time job.
I had my own account where my own earnings went, and his went into a joint account to which I had a debit card, but not access to the account online. As I do his invoicing, I knew how much was coming in, but couldn't see what was going out.
Then one day I went to buy something in a shop and the card for the joint account was declined. I tackled him later about it and it turned out he had fallen way behind (tens of thousands) on the tax bills and had made a deal to pay ridiculous amounts in a short period of time. Our account was overdrawn and we were paying huge penalties. Yet with the money he was earning there was absolutely no reason to get into this situation, it was down to utter incompetence on his part. And his accountant didn't tell me the situation.
I insisted on him showing me everything or I would walk out that day. It was a total mess but I spent hours and hours doing 3- year projections as to how things could be straightened out eventually. We are not there yet. Am I bitter? Hell yeah.
What could have made a difference? I think if (when he was having his temper tantrums) I had insisted on the financial situation being made clear to me, we would be in a better place now. I realise now his behaviour was out of fear as he couldn't manage things properly but wouldn't admit it. If he had, I might have more respect for him. He regrets his behaviour hugely now but that's not much help really.
I don't know if our relationship has a future, but right now I think we'd lose out financially if I walked, so my priority is to get that straightened out. It could all have been so different. So I feel older and wiser, but quite stuck.
My advice to you, based on my own experience, would be to go nuclear on him. Tell him if he doesn't level with you absolutely and completely, that you're out the door. And follow through - if it means you have to spend a small amount of money to stay in a local hotel or something, it will send a strong message to him. If he doesn't cop on, the relationship is dead anyway I would think. But if he comes clean you might have a chance.
You may find this article on financial abuse of interest -
www.huffingtonpost.com/ginger-dean/financial-abuse-6-signs-a_b_5627463.html
Good luck, I feel for you.