Was she acting? What's going on?

Hi everyone :)
I've once had a really weird experience with a girl, and I still wonder what's going on. I can't ask her directly, I don't want to make things worse. I'd like to hear your opinion.

Some years ago I met a new classmate. She was pretty cute and seemed like a nice person to me. We had some nice conversations, but nothing special. Then I had to screw it by telling her I liked her...
From that day on we never really had any good conversations anymore, but I took it as it was. Some weeks later I tried talking to her over MSN to see if I could just say 'Hi'. Well, probably not. She made it very clear that she didn't want to have anything to do with me, no talking, no nothing. I decided not to ask questions, but just to accept it.

Not to long ago I decided to try it again, but now I'd just send a mail. I had some help from a friend to write a good mail, in which I apologized for anything I had done wrong and that I'd like to be friends with her again.
I guess that wasn't very effective. She just told me again that she didn't want to have anything to do with me and also that she doesn't want me as a friend, since she already has enough of those (she really said that).

I gave up on her a long time ago. She became the 'popular girl' type, and that's exactly what I'm not looking for. Even though I've given up on her, I can't help to be confused by these events. It seems like things are okay when we're at school, I even remember her laughing with me once. Maybe that was fake? Maybe everything was just an act. Maybe she's always hated me, who knows? I can't ask her. I guess I will never know.

If only I could get an awnser, I could finally let it rest. I don't need her love, I need to know what's really going on in her mind, I need to know her version of this story.
Maybe I should just forget it? It would be best, right? What do you think? About this whole situation? What could she be thinking? Was it my fault?

By the way, I don't really understand why this post was moved to the Dating Talk forum... I never dated her and I'm not going to. Odd stuff.