i accidentally told my friends sister that i smoke?

ok so i told my friends sister that i smoke. he's really mad because of reasons he wont seem to tell me. his sister and i used to be very good friends back when i was in my longer hair phase, but she has some serious mental issues and she is bipolar as well. she doesnt have a facebook anymore and i dont have her number. im trying to make it right!! i expect that my friend is angry because i told his sister that i smoke and she might assume that he smokes now...she may already know im not quite sure. but im feeling really depressed because im an idiot and i really wanna make it right! help me out!