How can I get over my ex who's dating someone else?

I dated my ex for a year and then he broke up with me and came back and we dated for a month and broke up with me for the same reason he said that we both have changed and we really didn’t get to talk all that much because he was working so much. I miss him so much I can’t get him off my mind. When he broke up with me he promised we would still be best friends and he’d still tell me everything like he use to but since we have been broke up I feel like he has changed and is no longer the guy he use to be and we don’t tell each other anything about our problems or anything I feel like he has no time for me or anything. Also he is now dating another girl now and I hate this girl so much because she caused so many problems between us when we we’re dating and didn’t like the fact that we we’re together I feel like she got what she has always wanted him all to her self now. I told him that I found out since him and I haven’t been dating that 3 guy’s like me and I told my friend that I think it’s time to move on now and he got really upset over a comment I made and said well why should you care you moved on now but just the night before I cried to him about how much I miss him. But it seemed as if he got upset because I told him 3 guy’s like me he was like ok whatever bye I just don’t get it. I don’t know what to do try my hardest to get over him and move on? or just wait to see what happens please give me your advice.