If you use Facebook, you ought to know how to reply to a message sent to multiple people. When you type a response, the button clearly says "Reply All." This means your reply will go to every single person the original message went to. You don't want to do this. You may think everyone wants your address so we can all send our wedding invitations to you, but you would be wrong. You may think everyone wants to know about the intimate details of your life that are only relevant to the original sender and really ought to be kept private, but again you'd be wrong.
I know Facebook changes things a lot and will probably change this someday. But we can figure it out. It isn't that hard. Seriously, it's 2010.