I can't get over my ex?

I met this boy just under a year ago, we clicked straight away, can't explain it really, we just had so much chemistry. after two months or so we started dating, it was the best relationship i've ever had, he brought out the best in me, we were perfect. no one else seemed to agree though, we ended up finishing because everyone got in the way and made it so hard for us to be how we were when we're alone. from the moment we finished we didnt stop speaking, we still stayed unbelievably close, afew months later we admitted to never really getting over eachother and wanting to get back together, we went out and everything was just like it used to be however once again everybody got in the way and we never became boyfriend and girlfriend again. we still talked though and we know eachother inside out. its now been 9months since the first time we broke up and i just cannot get over him, its got to the point where always thinking about him is actually scary now, because it feels like he never goes away. every night i dream about him, i can never stop. its constantly upsetting me and i just cant let it go, i have tried everything..deleting him off social networks, avoiding him and trying to date other people, but everytime i decided enough is enough something happens like one of our movies we used to watch together will come on so he'll ring me, or i'll walk into a shop and our song will start playing and all the memories come back. i just don't know what to do anymore, it sounds so silly but its actually killing me:( what do i do?