I know it sounds a bit "right on" and preachy but you need to be comfortable with being on your own before you can get your head together and be completely OK about getting on with the rest of your life. I came out of engagement no 1 (there have been 3) after 4 years and it took me a while to work out who I was outside of the relationship; I was only 18 when I met her and that was just after leaving home and being disfellowshipped, so I had grown up alot in those 4 years and a large part of my personality was invested in that chapter of my life.
I ended up going through a few short term relationships over the following couple of years before I stepped back and took a while to concentrate on enjoying being single and all the stuff I could do as a single person that I couldn't do when I was part of a couple (staying in bed all day, going out with my friends when I felt like it and generally being myself). Getting over it happens slowly and part of that is remembering that you operated just fine before you met that person, and will do again for a long time after they have left your life.