First off I am not sure why you have a facebook and you don't want people to see what your putting on there. Personally I use social networking sites for just these kind of people, old school mates or people I meet randomly. When it comes to my actual friends I will just E-mail them pictures and updates on my life, not put it on the facebook.
I find this eliminates you having to worry about what people see what. Still I am not sure what you are hiding from this girl, I would have no problem adding her. Different strokes I suppose.
Adding someone on facebook is pretty meaningless. For the most part you will never talk to these people, even though you are "friends" on the internet you are never gonna be actual friends. Also I know you can find out when someone "de-friends" you on facebook, I am just not sure how easy it is to find out.
I don't think it show up on your wall or anything, but if you go to that persons profile it is fairly obvious if you are still friends or not. If you want to keep in touch with her I would suggest old fashioned E-mail.
The proper etiquette is for her to return the ring. If the man cancels the engagement, she is allowed to keep it.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.