I dang near love my best friend?

ok so im 16 and so is my best friend and last school year i fell for her pretty hard and started talking to her and walking with her to cles and junk and eventually she started to like me and then next week i dont know wat happened she like stopped liking me and i was puzzled and sad i mean i told her how i feel and she didnt want to date just yet and she said to wait for her to decide...and she never decided and went out with someone else but i got over her and all that but we were like best friends and talked and all of that again... well just recently ive started to fall for her again (i always had a little crush on her)and she likes another guy and there not datin and if i tell her i think it will ruin everything i have and i dont want to mess this up again and i would love to date her cause shes just so awesome i have no clue wat to do and its just driving me insane should i tell her? i mean if i tell her im afraid its going to ruin everything and ill be heart broken... HELP