Rules, actually boundaries, without consequences are pointless IMO. All it tells the A in your life is that you don't mean what you say. Until you are ready to set and enforce consequences for behaviors you find unacceptable, don't bother setting boundaries.
Boundaries are also not to control someone else's behavior. They are to specify what you find acceptable and what you will do if unaccpetbale behavior takes place. Your boundaries are for you, not your A.