Aw! Break ups suck big time. So sorry you are feeling lonely about it. Try to remember that it isn't really him you are missing. You are missing the dream you had about what this might have been. We all do it, project onto a situation what we dream and wish and hope for it to be.

I am glad you are on here, there are lot's of ways to keep yourself occupied and your mind busy. It is harder to be lonely when you know people care and understand.
Take heart. You dodged a bullet. Count yourself a smart and lucky one too.