Confused about my uality?

I know this is a much-abused question here on YA but I figure most of you will have something comforting or helpful to say. I'm a 16 year old girl, and I've always been sure that I've been straight. I've dated around and never had a doubt about my own uality until now. I recently found out one of my friends is , and I have had platonic relationships with s and bisxuals before. But the thing is, right when I found out, I felt attracted to her, but not just in a friendly way, ually too. I'd go so far as to say I have a crush on her. However, I've NEVER thought of her has anything more than a clmate and acquaintance before I found out. In fact, I've never even thought about being with another female in the romantic sense before. I don't know why I'm attracted to her either. I'm not afraid to tell people if it turns out I really am, but I'm more concerned that this is just a phase that will p. I'm also reluctant to say anything to her, because we've been friends for two years and I know she asked another girl out, which does upset me a bit. What to do?