am i bisexual?

If you got a crush on boys AND girls, I think you are.
But she's your best friend... so maybe you love her very much as a friend and you love her so much that you think you are falling for her but actually it's just a proof of a really close friendship.
Well, I don't know. I had a crush on my best friend, too (a girl), and it was really hard for me. Maybe you are different, but for me it was the moment I knew that I'm bisexual. Then I got over it now we are even better friends. I think I wasn't really in love with her...
But if you're sure you are, I think you REALLY you should talk to her. If she's your best friend, she'll understand it (My friend understood that)...
sorry, that doesn't anwer your question, but i care because I think I know how you feel.
so... I have to give you an answer...
...
congratulations, you are bisexual!

If you have feelings for both men and women yes you are bi. If you only have feelings for one women, then you probably aren't. In my general experience.