Guys, I need some help here.

So there is this girl that is crazy obsessed over me. She is clingy, suffocating, and frankly, it's draining me.
There is this dance place, and I like going there. I've gone there almost six months again, and never has there been any real issues. Recently, there has been this girl who is crazy over me. I don't like it, I want it to stop, and it is taking the fun out of this place that I love.

She managed to get my number, and she calls me cute and attractive every single time there is any sort of communicating. From a guy who has never been in a relationship before (I used to be ugly, and trust me, I mean it), puberty has been a weird time. Perhaps it would have been good to mention I'm 16, and she is 14, almost 15.

The last thing I want to do is hurt her. This has happened before with a girl who was crazy obsessed over me, but it died out as soon as I figured out that she was trying to cheat on one of my really good friends.

I wish I had this kind of dirt to just end it, but I don't know anything. I know that is terrible to say, but it is the fastest way of ending it.

I know what some of you are saying, "Do it! She is obsessed over you!!" Trust me, nothing good happens from this sort of thing.

So now you kind of know the premise, I have a few questions.

1) How should I go about telling her no?
2) How long will she be hurt for?
3) What are the down sides of that method?

Please reply quickly, and please no BS answers. I don't need this with this stress.

Thanks in advance,
Mayson