Is it normal that i am in love with my best friend?

So, i've been 'best friends' with this guy for about....a year? And in the past couple of months, my feelings for him have grown stronger and stronger. I don't remember when i first started crushing on him. But I remember how it was before, we just hung out, goofed around, had fun. But now it's so different. When I am away from him for too long, I miss him so much, it's like a piece of me is missing, my body aches in places I didn't know I had inside of me. I have never fealt like this before, about anyone. I would never tell him, out of fear of losing our friendship. I don't even want to imagine how I would feel if I didn't talk to him. I don't feel like it is normal. My heart aches every second, every minute, every day. Is it normal that i don't want to put our friendship in jeprody, even if it brings me unhappiness, him not knowing how i feel?