My best friend is making me curious...help!

[curious]

I am recently curious about my best friend. I have never thought about being gay before, but that being said, have never really had a serious relationship with a guy. (I'm 29yr female) I've had lots of random flings and sexual encounters with guys but not many relationships. My best friend and i live i a small town and don't meet many other people. Recently she's been down about work and life ect so I have been there to comfort her. But along with this, I seem to be falling for her! Is it just an emotional thing or does this mean I am interested in her? We do everything together and get along so well...hence best friends. I am not sure why I suddenly seem interested in her. I am not sure how to tell the difference if I really am or if I just care about her alot and don't want her to be sad and somehow think that physical contact will comfort her. (Neither of us are very touchy feely type people- don't hug eachother or others, mostly keep to ourselves physically). I've never reached out about being gay before but this is really troubling me. I can't afford to loose her friendship if I go to far and she's not into it. I don't think I'm into girls in general, I just seem to have a crush on her. And yes I find her very pretty, always have. Please help me!