How do I get over someone who used me for ?

Ok, I know a lot of girls (and guys too!) have probably gone through this too...but I dated someone who I really liked and cared about...We had very early on and kept seeing each other for another two months and we always had fun. Even though we were never officially in a relationship, I thought he was sincere...He is very charming and hot though, so I think he just might be good at making girls fall for him. Anyway, he stopped calling me (without ever giving me an explanation!) and I found out that he's seeing someone else now...It's been over a month since I last seen him or heard from him and I'm still really sad :( Any advice on how to get over him? I try to tell myself that he isn't worth the heartache...but I can't help but feel so hurt and taken advantage of...Help!