the only person allowed to go into my fridge without asking is my boyfriend. He's pretty much become to adopted son, so it's ok. But he has sense enough not to drink 3 cokes and eat 10 pizza rolls.
I don't touch anyone's food without asking (aside from my boyfriend's! it's only fair. plus i buy groceries for him too). Not my best friend of 15 years, not my grandmothers, no ones.
I really think you and you're boyfriend need to talk this through. Whether he feels the same as you or not, you need to be on the same page as to what to do when he's over.
I do think you might have been a bit over the top is saying how mcuhe owes you and so on. I think you could have said something a bit more tactful/subtle. how about, wow, you really did help yourself to all of my food didn't you? Looks like i need to go buy more groceries. Imo, that is better than You owe me ten bucks for the pizza rolls and 4 $ for the coke, pay up!
It's a rough situation... family is hard like that especially when it's not you're family. Either way, talk it through with you're man. If you're not on the same page, and this happens again, you're likely to loose you're shit doubly, then you'll look like a crazy woman. thats no good for buisness.