should i confront my best friend about this (long story)?

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okay so there's this guy that i've liked for almost 2 years...we're reallllyyy close friends. i've never really admitted my feelings to him because i didn't want to ruin our friendship and he just means a lot to me. and throughout these 2 years, i've told my best friend every single thing that happened between him and me. like how we always stay up talking on the phone, how we tell each other everything, and just things we do. so my best friend WELL KNOWS that i'm really into him. if anyone, she's the one knows every single detail.

i've also been keeping her up to date on how i'm trying to stop liking him because i don't want to ruin things.

but recently, my best friend messaged me and she's like "oh do you still like ___? because i think i like him." and i'm like wooahh there....
i told her i didn't like him anymore, but i didn't tell her why. the only reason i said i didn't like him is because it would be super awkward if we liked the same guy. but i do still like him....

and now, she's ALLLL over him. she messages him everyday on facebook, she's always talking to him at school, and now SHE tries to stay up late and talk to him.......that pisses me off the most lol. and it just really hurts watching...like it's hard enough seeing him talk to other girls,, but my best friend? well i thought she was my best friend...
and EVEN IF i didn't like him anymore, i still think it's a pretty b-tch move of her to do that to me....

but i feel like it's not like i can tell her who she can and can't like. so i've just been playing it off and pretending i don't care. i don't want to start any drama, and i don't want to ruin my friendship with my best friend. or "best friend"... but then again, would a best friend really do this? i've been friends with her for 3 years. and if i tell her about this i think it would make things really awkward and possibly ruin OUR friendship. we're also in all the same classes and clubs at school and i'd have to find somewhere else to sit at lunch lol.
plus, i always told myself i'd never let a guy get in between a friend and me. and it's not like i ever even went out with him, but he's really special to me...

do you think i should confront her about this? and how would i? or should i just let it go?
we're 15 btw if that matters.