I'm sure he's not letting you see HIS because you won't put his name on YOURS. This is a vindictive thing he's doing -- he's trying to get EVEN with you. Trouble is, you have no idea what he's spending his money on, and all that money is SUPPOSED to be both of yours -- not just HIS.
His thinking is all screwed up. Have you two ALWAYS separated your funds? Have you always had a separate account without his name on it and have you always had YOUR money and he always had HIS money? Was there never an account that was considered OUR money, i.e. for the two of you? Who pays the bills? What account does that come out of? Does he just play with his money?
If you pay all the bills and he just plays with his money, then by NO means should you put his name on your account. But like I said, he's just being vindictive because his name isn't on your account. And I assume it's his spendiing habits that is the reason. He sounds like a little kid -- give him 5 cents and he'll go buy candy.
You need to know how much debt he has incurred. That's a given. If he should drop dead tomorrow, you'd be liable for this. He needs to let you see this balance!!! He's being irresponsible.

I don't blame you for being angry! I would be too. Best of luck and God bless. Hugs, Lee