I no longer share anything personal on Fb. I'm happy to say that I barely use the site at all anymore. About 1 1/2 years ago I shared something personal, thinking that a few close friends would see my post and offer some friendship, some support. Turns out that loads of people lurk on Fb and the sneaks got all up in my business. In short, a disaster for me. After that, all I share is a very occasional comment if a celebrity dies. I wish people a happy birthday. Pretty much it. I miss email as a form of communication and I'm truly sorry I ever joined Facebook.
On PC? I openly share because I trust the community here. My only issue is that I get lazy about writing long posts. Sometimes I'd like to share more than I do, just for that reason.