I struggle with this a lot too, and just letting people get close to me in general. That ever present concern that if I share too much with them, they will use it against me somehow.

I've finally let myself develop two very close friendships...but it's been so very, very hard. I found myself testing the waters every step of the way...it's taken almost 4 years of knowing these two people to develop these friendships.

Perhaps you can start small...get to know some people that you think you might like to be close friends with on a more superficial level first. Find something you have in common that isn't too "risky" to explore more deeply. Build the friendship on that first. Go to a movie or out to lunch or to an event with a person...and then you can escape back home and evaluate the outing, see what you can build on. As you build that common ground up, you might find that you have something else in common you can build on as well....and just keep letting things grow. You don't have to meet someone and instantly tell them everything...it is okay to start slow and build trust and test the waters as you try to build closer friendships.