My girlfriend hit me outside a club, did i deserve it?

I got into an argument with some girls over queue jumping. My girlfriend was standing next to me, she wasn't involved in the argument, she was talking to one person of the other group of whom I was arguing with. She asked my girlfriend where's she's from, my girlfriend said London, then she called her a low life and a loser. I instantly got enraged, and said "thats rich coming from someone who's white" my girlfriend slapped me. I mean did she really have to slap me? I admit I did have a lot to drink and I probably shouldn't have said that but still