Make it simple, and tell him " I am writing to notify you that, to this date (put date), you have failed to pay the rent of (put sum) for the months of (put months and year). If you do not comply with paying immediately for the rents owed, I have no choice but to file a complaint with the Landlord/Tenant court. You have one week to respond to this letter and pay up." Then proceed to file the complaint with the court in your town or city. You don't need a lawyer. The marshals will do the evicting for you if he doesn't pay you. Of course, once he is gone, there is no guarantee he will pay you for the back rent, but at least you rid yourself of this parasite.
