If I were in your shoes. I would look on-line for discussion groups of people with similar problems. You shouldnt trust the advice, but it might give you the lay of the land. (Dont trust me either. I'm thinking off the top of my head.) Try to find a class action law suit that you could join, especially against your school.
Often the collection agencies are subcontractors to the federal agency actually guaranteeing the debt. Maybe the feds can give you some relief, like forbearance. Unlike a private creditor, they are often able to give you reasonable courses of action.
If I were you, I would get some legal advice. Maybe they cant just have their way with you.
Fight back.