How come I keep thinking of girl that wants nothing to do with me?

I never had a girlfriend and this one girl was the closest I had as a relationship. I talked to her on penpals now. I was from Massachusetts and she was from the Connecticut new York border. We did meet once at the mall and she gave me a kiss on the cheek. The only time a girl has shown me affection. She said she would date me. But the next week we got in a huge argument saying she doesn't have any time to meet because she can't afford the drive. I fear driving by the way.

Anyway I keep thinking of her lately. I even cry myself to sleep. I have major depression, She threaten calling the cops if I emailed her so I stop. I have that urge to email her to ask me to give me another chance but afraid she will call the cops

I havent talk to her since last August. I dont know why I cant get over her? Its probably because shes the only one that was realistically thinking of giving me a chance.