Simon's right, they constantly change the privacy settings, and everything goes back to their default (and very open) mode every time they do!! Obviously Facebook doesn't understand what it's like to try to leave a cult! They have this dreamy 'people should be open about their lives' mentality which is just not practical for EVERYONE in the world.
Seriously, if you are going to post stuff, be willing to face what may happen. Sometimes that's liberating, but it's scary beforehand and during.