Why do you have feelings for your best girlfriend if you are a girl too?
Women by nature are more emotional (and I mean that in a good sense). They are more in tune with their emotional selves, and more likely to allow emotional attachments to people, romantic or not, than most guys are. So there is no harm or problem in having feelings for another woman. Embrace the fact that you are emotionally able to do so - many men can not do this, or are afraid it will threaten their 'masculinity' if they admit to feelings. Enjoy it and don't feel guilty or weird.