If you don't want it broadcasted don't put it on the net. Simple.
Sometimes you need to say or write things down as a form of coping or dealing with your surroundings and situations. It may help you understand things better or earmark the matter for future discussions or whatever.
Very similar to journal writing but it's digital and can be multimedia. The problem then lies on accessibility of such a post. Is the site you are using privacy heavy? For sure you shouldn't use twitter, Facebook, Google+ for such things. Who can view and comment on it? A totally private blog shared with select people protects the post somewhat but not totally.
A digital online journal can be both liberating yet dangerous as it is online - if your pw get's hacked then the poop will hit the fan. If you leave your browser open and someone sits down & reads your bookmarked stuff then your screwed. So is it better to keep a paper journal?
I'm starting to think it is... It then falls to where to hide the physical journal itself. It's easier to toggle a "private" switch isn't it.
For now I will use private posts.