You are right in thinking that this situation is unfair for you, cause it is. Most of us often divulge a lot about ourselves to others over time. While I would still say that some people do end up using the information about you to either gossip or to get their motives fulfilled, it does help ease the load on ourselves if we share. In my country, a very common proverb is that our happiness increases when we share with others, while sadness decreases if we do. So its okay, you have the right to do whatever with your own information. Your family might have some toxic traits if they are having these double standards, so be a little careful and take care of yourself.