Bi?? Help! crushing on bff

okay so I have a bestfriend who I've known for about 3 years now & I've always thought she was beautiful. Recently I've been becoming bi curious. We always tell each other about our boy drama & she's mentioned thinking a few girls were hot, but idk if she's bi. I'm starting to get a crush on her and idk what to do!!! what should I do? & does this make me officially bi?