Oh my god. please help me.

I'll have to type all that there is...here I go.
I transfered to a new school a few weeks ago, away from my best friend, Zach. I had this insane crush on him, and I keep getting these pangs of...pain, just like hunger pains. I miss him so much.
Then a...

week ago, I saw this kid on my bus, in my grade. He was the most beautiful guy ever, I swear...anyways, he was looking at me, not quitw staring, but...looking. Then he just turned and looked at the window. My God, though. He's tall, blond, and just...wow. Now over the past week, I've been...looking for him, in every hallway, and when I see him, my heart pretty much explodes. I feel really...wierd for watching for him so much...but sometimes I catch him looking at me. Just sometimes. I don't even know his name, and he's never even spoken to me. I feel so guilty for being attracted to him...not that he would ever want me. I'm not what someone would call attractive, to say the least. But I can't have Zach, either. Just the other day he...broke my heart. I thought all this time he had a crush on me...but he told me 'he loves me like a sister'. So...he doesn't even like me. I'm just so torn up...oh, and on top of it all, I have extremely low self esteem, not that I show it.
So why is this kid looking at me? Does he like me? What do I do about the whole Zach thing? What do I do??