He called me fat!! what should i do?

we were talking & he said he got in a fight, I said "wow did you beat up the guy??" & he was like "why are you so surprised??" so i told him that he didnt have much muscle (playfully) than he said "you'll see my muscles @ summer" & i said "if you had muscle they'd show underneath clothes 2" & he said "so you've been staring @ me as you know i dont have muscle" & i said "you stare @ me too" & he said "yeah but i stare at you all the time but you staring at me is kinda new" oh btw there was this girl he told he liked her a while ago but all his friends keep telling me it's because he wanted 2 make me jealous, & we were silent 4 while so just 2 make conversation i asked him "did she say she liked you??" & he said "kind of she said she wants get 2 know me" & i said "well let's hope she doesn't lol" & he said "yeah she'll break up w/ me as soon as she gets 2 know me" & we laughed & stuff than he said "you're supposed 2 say no she won't break up w/ you here" & i said "why it's true" & he said "why would she break up w/ me" so i told him he was not handsome, a major jerk, an alcoholic & a perv but jokingly. so he said "nope i'm not a perv" & i said "yeah and i'm a fairy" & he was like "with that big stomach?? i don't think so..."& i said "i'm not fat you'll see @ summer" & he said "like i care whether ur fat" or not than i said "oh i think u care or you wouldnt bring it up" & he said "maybe". than he's like "what was your friend's name again" (i have a friend who's really hot he'd told me she was cute b4) i was like "go ask her" & he said "cmon tell me" & i said "no that's what you get 4 calling me fat" & he said "you're so thin that you're starving OK?? plz tell me her name??" & i said "no" so he said "dont talk 2 me" & i said "fine like i care" & he went off in a huff. i mean wtf??? do i apologize or should he apologize 4 calling me fat first???