Friend??

Ok so I've been with my bf. For 2 years and last night we went over one of his friends house whom I already know but his friends mother, gf, and sister were there also. (His friends gf doesn't like me for no reason at all she doesn't even know me) Anyway so when introducing me to everyone he introduced me as his FRIEND?! He's never done that before while we were in a relationship. I was really pissed off but I didn't say anything. So when we get back to the car I just asked him why he introduced me as a friend he said that he didn't mean to! I'm sorry but that's not something that just slips your mind. Eventually the conversation turned into an argument. Although we live together we haven't spoken since last night and he slept on the couch... I mean am I wrong for being mad? I can't believe he has the nerve to be mad at me. Am I overreacting?