Mamma knows?

Hello. Ive been in the closet from the family since I discovered I was gay.I started my own internet cafe not too long ago and I've been bringing my lesbian friend quite a lot. She is cute and just all around cool. My mom likes her and she asked me if she is my girlfriend or I like her. I said no and that she is lesbian and already has a girlfriend.2 days after that while walking together she just asks me out of the blue: '' Son, do you have a girlfriend or a boyfriend? '' I almost got a heartattack when I heard her ask that. My panic answer was why? and then I said to her no, Im dating someone from the capital.I don't understand this situation, does she know? O_O