Just a sad song, or are these the good days?

I can't sleep and it' one in the morning. I'd like to be able to blame it on the insomnia, but tonight it's something more.
It's her.
I don't understand how she can make me cry when she's not even here. I thought I was ok but in the dark all alone your feelings that you manage to hide even from yourself manage to take hold. It's shocking and terrifying knowing what a hold one person can hold over you. I don't think that twenty years from now I'll scratch my head and try to remember her name. This is something that has touched and changed me, enough that I will never forget. I know I care so why is it so hard to give in? Is she right? have I changed that much since I've been gone, so much that I don't even know myself? Or is it that she is part of a world I left behind, and the one I now am in is much more selfish?
I don't know. All I know is there is no end of things that make me think about it. A blanket, a song, a word, a smell. These things all conjure up ghosts of extremely cherished memories. If I was so happy before, why do I find it so hard to feel happy now?