Unbelievable.
Starting point in any relationship should be a joint account for joint bills.
Individual accounts for personal spends.
When one of you stops working SAHM/SAHD the working partner's whole salary - and to be fair CTC/CB needs to go in. When bills/emergency cash covered... it goes 50/50 "spends".
When you start work your salary goes in too (childcare comes out) and hopefully you both get a "spends" increase.
Remember if you chuck him, he'll end up paying only about 20% in CSA if you have 2 kids. As far as the marital settlement goes, you'll get 50%, probably. But that doesn't mean you'll keep the house, nor that he'll end up paying mortgage/rent for you.
Can you get access to statements to track what the bills/shopping/regular payments are? From that, work out what his cut is [note, you have to allow his travel to work as a joint expense :)] but see what his spends are.
If he's not going to discuss this, he has little respect for you and reluctantly you may have to go further.
From a bloke's perspective, he will feel pressured; he will feel guilty. Expect some bluster, but just say it needs to be discussed, and let him choose a time within the next couple of weeks. Don't get into a shouting match with him, as that will let him self-validate his response to you.