Help! ive fallen in love with my best guy friend!?

it all started when he grabbed my hand while we were walking... confused, i let go.... and now i realize that all that bickering and insulting and whatnot between us really was me falling in love with him. how should i break it to him? im outgoing, but when it comes to stuff like this, im really really shy and fearful of rejection... even my friends call me a tease bc i have a really really outgoing and carefree outer mask... help me please!