Firstly, I understand the sense of violation that you're feeling. I'm sorry that happened to you. Now who is Lars? There's not a profile here by that name. That wouldn't stop someone from skimming this site for links, though.
One of my clients at the office is our Information Security team - the people who investigate and build protections against threats to the integrity and safety of our data and systems. I work closely with the communications manager, who told me the other day that FB is not at all secure and because of what she knows, she would never create a profile there. She said that if you do have one, you should never accept a "friend" from anyone that you don't know personally. Besides gleaning personally identifiable information, FB can be a gateway to viruses and other malwear.
For individuals and groups who are using Facebook as a form of advertising, I suppose that presents a kind of dilemma. I'm not sure how you protect yourself against that sort of thing, except to limit the amount and value of stuff you post there that people can do evil with.
Keep us posted on how it turns out?
Regards,
Rex.
At any moment you must be prepared to give up who you are today for who you could become tomorrow.