Best way to get over someone?

I was with a guy for about 4 months and we became close and he was my person. In June, things went sour and he left for college while I am still in high school. I saw from his story before I deleted him that he was partying and didn't care at all about my feelings. I know I do not need someone like him in my life, but I miss him as well even 2 months later. Any advice for not thinking about him?