How big is your school and are you going to take similar classes? If your school is large enough and you have different concentrations, there is a very good chance you won't run into him much unless you plan it. I live about 2-3 blocks away from some people I go to school with, and I have yet to run into them anywhere in my neighborhood, if this helps put it in perspective.
It sounds like you have more problems going on. For starters, while I understand that school is your time away from him and how necessary that is, what will happen when you are finished with school? I really think you should, before you even tackle the school issue, tackle the issue that you feel that you don't have much time to yourself.