My boyfriend gets angry all the time - PLEASE HELP?

I really need some advice. My boyfriend always seems to get angry and usually over small or weird things, and I don't know what to do. Like today, for example, we went grocery shopping. We barely had any groceries and he started freaking out about paying for it, but in a sort of passive aggressive way - mumbling about it, talking under his breath, but not telling me exactly what he was saying when I asked. I offered to help pay, but he wouldn't let me because he knew it upset me when I used to have to pay for everything last summer. So I didn't really know what to do, so I told him he could go get my debit card out of the car if he wanted. He refused and started becoming really angry and saying "this happens everytime we go grocery shopping" as if it was my fault, but it clearly wasn't . So I went to go sit in the car while he paid for it because it was starting a fight, and when he gets in the car, he says this, without emotion, "I'm sorry, although you probably hate me." And after this stuff happens he always sighs and stuff all sadly. Nothing I've done works. And PLEASE don't tell me to break up with him and find a real man, because that won't help either of us, and that's not love. Thank you.