Saying what you mean and meaning what you say

I think that sometimes people don't say things, or maybe aren't honest about their feelings, because they don't want to hurt someone.  I'm usually on the opposite side of that fence because I say things, often without thinking, and then it either comes out wrong or it's just too blunt.  And that hurts too.  I guess I struggle with thinking about what I say and how it will affect someone.  But what if the things that are left unsaid hurt just as much as what is said?