buttercup, like your name BTW, trust has to be earned in my opinion. i too was often hurt by people who i had chosen to trust. what i discovered in therapy is that there are some people whose traits are not worthy of trusting. so i learned ways to decipher "good" people by what i observed about them, did they talk about others behind their backs?, were they compassionate towards others, etc. basically people who exhibited my own value system. so i sifted thru the people i knew and found those who i felt fit well with me. i do have people who i call friends but not all do i confide in, in depth. we benefit from setting healthy boundaries with people we are comfortable with. our true trusted friends, for me, have to understand boundaries too.
this a good article that may help you-
hope this helps. you needn't just jump in over your head for fear of a broken trust in the past. test the waters and as you feel more comfortable with someone you'll know.