All right, I feel obliged to help out a fellow Kevin here, although you've gotten good advice from a lot of other people here.

Firstly, stop with the stalker-like stuff. You =don't= have to comment on every single facebook post. Truth be told, you should probably stop commenting on all of them for a while. After some decent amount of time has passed, you can go back to like, commenting on occasional posts that you actually have reason to post on, but the "comment on every post thing" is really obvious to both her and to anyone she's friends with.

Secondly, you have a couple of ways to handle stuff. I think the first one is probably the more mature way to handle this, but I'd suggest the second way. It has a much higher success rate with younger people. The first one is to takl to her. Be like, "Look, I had a huge crush on you. I understand that you don't feel that way about me, and I'm getting over it. I really want to remain friends, but I'm going to try to leave you alone for the next few days (weeks?) and deal with these feelings." That's the more mature and honest way to deal with it, but it also requires people to be more mature and be willing to talk about difficult things.

The easier thing to do (and what I'd probably suggest given high school ages) is to give her a few days. Deal with your feelings, clean up your stalkerish tendencies. Then start hanging out again and pretend like nothing ever happened. Hopefully she'll pick up on the hint, and if she ever did act flirty towards you, she'll stop it (I had an ex who really didn't, and it caused me a LOT of emotional havok back in the day). Of course, it's possible that she never did, and that won't be an issue.

Best of luck. Things like that suck a lot .