How to move on from your first love? (not teenage love)?

We broke up with my boyfriend about a month ago. We have been together for almost 5 years from the age of 17 (he was 18). He has been my first and only love. We did break up 2 years ago as well, because he has found another girl, but he came back and I thought that after this we would never separate again. But he has found another girl again. We met twice after a month after the break-up because he has been calling me and telling me he was missing me. We spent the night together and I felt that he does love me still, but not as much as before. He is still with the girl and he does not call me for some time now, as I was too cynical about his new relationship. I try, but I cannot move on... I really cannot imagine my life without him and don't know what to do with myself to get over this. I try to keep myself occipied all the time, but if I just think about him for a moment, I feel so empty and so miserable. I know... time will help, but how to untill this time would come??? Thank you!!