Wow, I just came on here to make a thread with about the same title. I think your idea about keeping information about your life to yourself is a VERY good one. My life improved once I stopped giving my parents information about what I was up to. They only seemed to use any information I gave them for their own purposes. The less you say, the better.

And you are right, that knowing your parents are sick doesn't really make it any better when it comes to dealing with their behaviors.