How do I get over him?!?

I became really close with this guy that I've liked for a while and we became more than friendss but like, it wasn't official.. Then he left me to comfort his ex fir whatever reason. And that clearly means she's mire important to him. But me and him were like really close and it breaks my heart when I hear someone talking about him or if someone asks about us.. What should I do so that I can get over him and stop feeling so sorry for myself??:/