How to get over a serious breakup?

Me and my ex broke up on bad terms, he acted so different when he broke up with me, I ask him why is he acting different and wanted to do this when he told me he wanted to be with me? He told me nothing, no point telling me and that we are not meant to be. I know I made couple of mistakes by yelling at him for not always picking up his phone. When I'm in love, it drives me crazy when he stop doing the things he used to do. Maybe it's me that have issues or him, doesn't matter no more. I did tell him my feelings that I loved him so much. This is the first time I actually stop contacting him and its hard because I'm so used to talking and texting him. I feel so crappy right now, I'm actually hurting. I don't want to go out, I can't eat, I just want to be alone. I can't really focus on anything. I been through a couple of heartaches but not as bad as this one. I don't know whats going through his mind but I have to say we done so much together that I don't want to throw it all away but if I have to, it's going to be a painful journey! HELP!