Yelled at for using the word "Whatever"

Okay ladies, I need some advice. My boyfriends temper has been getting a little out of control lately and today I he was at the store and I asked if he could grab me one of the Starbucks bottled coffees while he was there, he said he was already checking out but then started getting really rude and snappy so when he said he was going to hang up and he'd see me at home I said, okay it's whatever, bye. Then I got a text of him yelling because he was furious with me for saying the word "whatever". He literally went off for a full ten minutes texting me how unacceptable that was and how he will not be made to feel guilty and all of this other bulkshit and I just don't think that's okay. He's on his way home now and I need advice. 😔😥