i still think about my most recent ex a lot. she left a big mark on me but at the end of the day it didnt work and she always made a point of telling me how miserable i made her, even though she still wanted things. i gave her the opportunity and she couldnt pick me, and by the time she wanted things, i had found someone else.
life moves on, but some people will stay in your thoughts for a while. just do what you have to do to get through it and things will get better in time. keep communication to a minimuml, preferrably nonexistant.