How can I stop stalking?

First I would like to claim that I'm obsessed. there's no denying that. I think i'm borderline stalker as well. It hurts to admit it. I hate this obsession with this girl. We chatted at school when i was depressed and I got to know her well, then as my antidepressants begain to work we seemed to drift apart and she didn't share herself with me anymore. I wanted more and got her number. I went crazy and sent 20 text messeges and told her how much i loved her and how beautifl she is. This cl has become a nightmare. Im starting to fail cl because of the distraction this girl is causing me. She is distracting and my grades have definitely begain to suffer. For some reason I feel like she wants me deep down. But I really really wish she didnt even exist because its causing me hell and i make a fool of myself. So today i tried talking to her and she was like its cool if i sit next to her but not if i talk to her or touch her? What is that all about? I mean if shes not going to drop the cl and shes going to sit right in front and twirl her hair what am i supposed to do? I mean shes cute and cool but now she is being a huge *****. i would do anything to jsut move on and get over it completely. but i still want her and i hate myself for it. Today we talked about the text messeges and she said she was freaked out and like that im a stalker and psycho and **** but she said its ok for me to sit next to her. part of me thinks she enjoys the torment she is putting me through. and i half like it and half hate it. but i still love talking to her. why do i have to be so damned mest up. i have had a hard past few years and have been an extremely lonely guy. for somer reason i thought this chick liked me, but dang im jsut trying to get through this cl. Im at the age where i need more. i need a relationship. im tired of being lonely. im a good guy who is very loving and very affectionate. i have no intentions of hurting this girl or doing anything to crazy but she has upset me and she has been being a *****. like she started the ignore game out of nowhere when my antidepressants started working and i became more confident. i know it sounds rediculous but i love chasing girls and i love a challenge. and i know its borderline stalking but my soul keeps hankering at me to keep trying to talker to her. just because i enjoy it so much. i dont know. im just going to try to make it through this cl without failing and keeping hope alive that a woman will come along and i can forget all about this. trust me i didnt choose to be like this. i like caring for her but dang i dont know what to do. i cant just quit thinking about her, i didnt choose this . please please please help me.