My roommate owes me $1,000!?

My roommate who is also my best friend owes me about $1,000 in his half of the bills, cash he borrows, and things I've put on my credit card for him that he told me he'd pay me for. It's been going on for months. He's on my car insurance and never gets me his half of the money, but I can't pull his car because then he'd have no way to get to work. I don't want to be a b*tch but I need this money. I can't keep covering him. I need the money to pay my own bills. How can I get him to pay me. Anytime I bring it up he yells at me, and throws a fit, saying that he "deserves" to go out to dinner, buy DVDs, and go to the movies. That's where all his money goes, other than gas. He hasn't paid for Groceries in months, I don't even include that in the money he owes me. I can't not buy Groceries because he badgers me into shopping, plus he has two kids who stay with us every other weekend and they need to eat. What do I do?!?!?!