To trust or not to trust?

Being a human, I have faults.  Many, many faults.  The one that constantly bites me in my big rear is my ability to trust someone from the beginning of a relationship.  This includes saying things in which I would expect someone to use discretion when further disclosing, or better yet, not disclosing at all.  This most recently bit me in the rear when I said something about a persons demeanor, how I felt someone was unnecessarily rude when I was a paying customer.  After I said it, I wished I could have taken it back.  I remembered when I worked in customer service.  We all have bad days and sometimes our frustration gets taken out on the innocents.  My bad experience could have been attributed to many factors behind the counter.  Instead of retracting my statement, I let it be, thinking nothing of it.  Until I get thrown under the bus for something that was misconstrued.  Do I make apologies for what I said?  Yes, I do.  Am I upset for being used as "evidence," a little, but I'm not going to make any excuses for what I said.  I said it, like I said earlier, I'm not perfect.  My mamma made the best comment last week, "we're all a little socially awkward.  We all say things we would like to take back, but we say it."  I think the worst part about this, is it hurt people.  People I care about, and people I consider my friends (none of which I said any comments about). So, here comes my dilemma.  Why do I trust people??!! 

I do understand what I said was what I said, I do take responsibility for that.  And recently I have stopped wasting so much energy hating/disliking/being angry at people.  But sometimes it's hard.  I should retract that, I'm really not angry at this person for saying what they said.  I'm more so upset at myself for not thinking before I speak and for always being surprised when I trust people, just to end up hurt.