I broke us up--now what do I do to get him back

It has been about four months since my boyfriend of 4 years and I broke up. The last two years of our relationship were long distance and directly out of college. I moved to the East Coast for a job and he stayed in the Mid West. I had some doubts and reservations about us. I am very career oriented and I did not know if I was ready to sacrafice the best city to live in for my career to move back home to be with my boyfriend. Needless, to say I ended the relationship due to these doubts. It took that time apart for me to realize that I did not have doubts afterall -I just needed to live life on my own for a little bit. Unfortunately, I really hurt my ex-boyfriend in this process and the thought of getting back together does not appeal to him. We were maintaining a friendship for awhile-however, he has begun dating someone else long distance and now will no longer speak to me. This girl is actually someone we both went to college with who throughout the time I was dating him tried to sabatoge our relationship. She is easily the only girl that I have ever disliked. So, his dating her makes the whole situation even more painful. I desperately want him back or at least a friendship for now. I am so heartbroken and it is beginning to truly effect my daily life. I need some advice.