Idk what kinda of stare this was, Helppp!?

Soo one day in art class me and my friend were talking to some guys in art class and one dude was flirting with me and then my friend saw and said "she likes you" but meant to say " you like her" her meaning as in me. and then when my ex heard, (he was sitting right next to them) he looked straight up at me. Idk what that stare was though, Like the moment my friend said " she likes you" he look straight up directly at me.