I in love with my Prince Charming?

how do i know if he lkes me......................................… friends with his sister so i would always see him there..............when i see him in the corridor, he always looks nervous and looks down when he sees me ................ and so do i coz im just madly in love with him....................its no crush believe me coz ive been crazy about him for about 2 years now. he is SO so shy............................... what should i do............i cant tell his sister (my friend) coz she is such a bigmouth and will shout it out in front of him SARAH LOVES MARK!!!!!!!! she is very immature like that...........please help i love him