When someone breaks your trust, don't feel stupid for trusting them. You didn't do anything wrong; they're just untrustworthy.
Trust is earned, respect is given, and loyalty is demonstrated. Betrayal of any one of those is to lose all three.
It is hard to believe that a person is telling the truth when you know that you would lie if you were in their place.
You can't always judge people by the things they done. You got to judge them by what they are doing now.