how to get them off your mind

My ex and I ended things very very badly about 4 weeks ago and I've been doing the best I can to keep myself busy. I go out with friends, I work out, I read, all that stuff but no matter what I do he's constantly on my mind. Something in every single one of those things screams his name in my head. I can't do ANYTHING without being reminded of him. I don't know what to do anymore:( Im tired of feeling this way. I miss him so much but I refuse to talk to him or anything like that. I need to move on and I'm trying but it's just so hard every day just feels so miserable and I'm not even sitting around moping about it.