When someone tells you some really personal stuff, it means 2 things. They really trust you, or they can't keep their mouth shut they have to tell someone.
If it happens that you are one of the unfortunate one, good luck. If I were the one telling you my secrets, I feel that I should know something bout you too. If I see that you don't tell me anything, it can be concluded in 2 ways too. It's either you are a very secretive person not wanting your personal stuff to bother you or you don't trust me, so you don't want me to know anything bout you.
If I am that person that people don't want to tell their stuff to, logically I'll shut up I'll not say a single word anymore. Surprisingly, this world has strange characters. Even not knowing a single personal stuff bout you, they keep on telling stuff, things I believe you shouldn't be revealing.
Moral of the story, you can never trust anyone. If you don't feel comfortable, don't do it. Don't tell personal stuff. Once that bond is broken, you never know where is it going to end to. Keep that to yourself and everything will be in safe hands. If you need to tell someone, tell that to someone who is outside of the group who can give an unbiased opinion. Others who know your stuff will have that upper hand. You have directly and indirectly lost.
Being ignorant is really bad. It needs to be balanced. It doesn't mean that my life is more happening with me telling you stuff. If you realize this behavior, it's good to put a stop as this is for sure a gap in between.