Embarrassed.

I'm 15 and for years I have been masturbating. I only ever told my boyfriend because I felt like it was something I wanted to keep to myself. But my boyfriend decided to tell his friends about it and his one friend texted me "whatcha masturbating to?" My boyfriend knows I wanted to keep it to myself, and I told him not to tell anyone. Yes I know its normal to masturbate, but I have the right to be upset, right?