I had a lot of issues back then that I have mostly gotten over now. I was suicidal, I was on pills for ADHD, and I was even suffering from delusions and stuff like that. I suspect some of these issues were a result of the pills I was on.
So when I first became friends with this girl, I did have a lot of problems. Admittedly I found her sexually attractive too and just something about her got me obsessed with her. At the time I thought it was love, but really I was just an obsessed stalker.
Even though she wanted nothing to do with me, I continued trying to talk to her. It eventually got so bad her boyfriend was threatening me and she turned a bunch of my friends against me. Eventually she even got the school involved and I got removed from a class I shared with her.
These days I don't have any of the issues I used to have, yet I'm still obsessed with this girl. I've blocked her on facebook, deleted her number, and I've even been trying to disassociate myself with people that talk to her. I've tried to convince her to block me on facebook herself too, since that would make it practically impossible to talk to her. Yet she always just ignores me when I ask her to do that.
To be honest I'm not even living in the same town as her anymore. Yet I still think about her all the time. I even unblocked her on facebook once and had a message typed out to send to her, before realizing I need to stop.

I know I need to move on, but for some reason I just can't seem to forget about her. I really just want to forget she exists and find a woman that will love me back, instead of obsessing over one that clearly dislikes me.