How to forget him??

This guy I dated before, we were off and on for almost a year and we liked each other a lot but he would tell me after her tried to get with me that he was back with his gf then would forget about me but after they break up he tried to get back with me but now he tells me that my friend is his new girl. The only reason he met her was because I gave him her information. Idk how to forget him even tho I try to ignore him