You are not wrong or unreasonable.
He does sound a bit like a man child though - my DH does work but is not great financially and is happy for me to sort that (he’s not that interested in the details, which is prob not great really) but then will stick to the budget we have agreed for each other’s frivolous spends. He occasionally goes over a bit (as do I) or we have one off things come up where one or other of us needs more, but it’s discussed and agreed. There’s no childish tantrums, silent treatment etc... your DH is unreasonable here, both in terms of repeatedly going over budget and in his reaction to you denying him more.
In terms of amounts, you have what you have - sadly none of us have that money tree. You shouldn’t have less than him, it should be equal. Then if I were you I’d save what ever you don’t spend from your share. Not give it to your H to spend. Then if you did need / want something you could get it. He needs to learn that if he blows it, there is no more. So you do need to stop enabling him to go over by advancing him more money - he’ll never pay it back or catch up, because he doesn’t have to.
I agree in relation to what his “pocket money” (for want of a better term) is spent on. I view alcohol etc as a luxury so if my DH (or I) want more than the small amount we’ve agreed in the weekly shop, it comes out of our pocket money. It makes neither of us alcoholics to buy more. I think the comments on that issue are just daft (although I have to say I’d personally not be happy for him to spend it on drugs). I spend mine on what I like, as does he. That’s not particularly unreasonable.
Your comments on the relationship are concerning - is there any love there or are you just staying for the kids ?
If it’s just the kids, I’d start to prepare to leave as soon as you can (even if it is when they are older). Don’t be getting into debt or you’ll be forever trapped.
If there’s love, perhaps sit down and discuss the budget so he sees there’s no more money. Then tell him his reaction is unacceptable and unfortunately due to childcare commitments etc, you are stuck with it in the short term until the kids are older and he can work. I’d also be suggesting that he does something to keep himself attractive to employers - maybe some part time education, training etc he can work around the kids ? Might also keep him out of trouble....