Does she like me back?

Right ... sorry this is a bit long ... I'm a 16 year old high school student. In August last year, I met this girl in my art class I'd never talked to before. We soon became good friends just through those 40 minutes spent together every day. I didn't like her back then since I was in a long-distance relationship with my girlfriend from Ireland. We soon became increasingly closer, often telling each other about our own relationship problems ... I was the first to know of her impending break-up with her boyfriend, and she was the first know about my breakup with my girlfriend.

After the two breakups which happened almost on the same day, we started spending even more time together ... every day after school we'd stay in school for an hour and just talk ... she chose to spend time with me rather than her friends ... granted, I've never actually gone to the movies or anything with her as friends ... but that's mostly because we've had almost no time with school and everything. But anyways, I was starting to really like her and I thought she liked me too ... I mean, the five hugs and the frequent kisses on the cheek to say bye had to mean something, right?

but anyways...everyone thought we were headed for a relationship (my best friend included) including me. I was very confident she liked me back too ... until yesterday.

A mutual friend came to me ... he asked me if I liked her, and I said yes ... then he told me to back off cuz she only thinks of me as a friend ... I don't know if he's talked to her or not, but he seems pretty sure.

So what do I do now? Do I go on and ask her in the future, or should I stop and give up? The second choice isn't gonna be easy because we have so many mutual friends and I can't just ignore her ... please help!