Having problems with a girl?

For about 6 months now, i have been hanging around with a group of girls, and i think i fancy one of them. She quite a bit taller than me, which is quite awkward as my face reaches her boobs, and i am in DESPERATE NEED IF ADVICE ON WHAT TO DO NEXT!!! I have my best friend who i've known for about 4 years now, and i havent told him yet because i wanted to keep my thoughts to myself. But then the girl i fancy tells me she fancies my best friend, which i am really jealous about. Which puts me in weird mood swings. I can't figure out if she fancies my best friend or uses him as a decoy and fancies me, as she texts me everyday for about 2 weeks now. She has been sad at times thinking about him though. I cant help but encourage and help her get with my best friend, i want her to be happy. If i told my friend, he wouldnt go out with her but the girl could hate me. Or i could watch how she works in a relationship at the risk of them falling in love. What do i do? I don't feel comfortable with asking her out yet, i still want to get to know her more. We were supposed to be going to the cinema tomorrow but then she started lying for some reason and changing the subject on texts. She says the film is new, tickets will probably be sold out, the film is weeks old when i send one bavk she changes the subject twice by saying that my best friend might of found out the girl fancies him. It gets more complicated everyday! I feel rejected, as the film was meant to be me & her, but then she wanted to do it ankther time with more people. Was i rejected? WHAT DO I DO????? Thnx for all help.