well they say out there that people are social creatures and cannot live without interacting with others. as seraph said before, you dont want to get to the point where nobody cares about you.
but again, its you decision what to tell and who. maybe you could just try to be a little bit more open with your friends(if you REALLY think the deserve it) and maybe tell them you were hurt in the past. maybe, if they are good people, they will understand you and try to help(that`s what friends are for).
if you think they cant keep a secret, or know that in the past, those people told somebody else`s secrets to other people then its normal that you cant trust them. try to get close to a friend or two, and share things with her/him.
lol and if they shared some of their private business with you, maybe they wont risk telling anyone what you said, fearing you may reveal their secrets as well.