I know she WAS into me, but is she still?

Okay, so I'm a 16 year old guy, not had many girlfriends in the past. She's a 16 year old girl and also my best female friend.

When we first met, she was in a relationship and I wasn't. I then got into a relationship just as she got out of her's, then I broke up with my girlfriend and she got with a new guy etc.

This has gone on for about a year and a half now, but now we're both single, and since I split up with my previous girlfriend (and a little bit before that actually) , I've really fallen for her. The problem is, since we're such close friends, I'm worried that I'm in the friend zone, and there's a fair bit of evidence to support that theory. However, a couple of my friends told me that she used to be really into me, and after looking back over our conversations and facebook messages and such from a while ago, I think they were right. So here's my question: Is it likely that she would still be interested in me, if I was to ask her out, or would she reject me and our friendship ruined?

TL;DR - She used to like me, but now we're close friends and I like her. What are the chances that she still likes me?