Friends, Dating, helpp,, please?!?

One of my bestfriends is going out with the girl I like. She and I are always talking,, we've been friends for a while. She knows I like her, and she says she likes himm, but she likes him too. I feel like she flirts with me all the timee. I mean I don't mind but.... She always like asks me why I like her, and put her name as my signature onn my phone, and we always talk about her.. I'm confused with all this stuff.,, and I'm worried that if they did break up, and she wanted to go out with me, what my friend would do. Any advice? Thanks!