Don't believe gossip. Ever. Even if you want to believe it. The person who told you may not be a liar, but that doesn't mean what he or she is saying is 100% accurate. Remember the game TELEPHONE, people!
Never let anybody else tell you what to think about ANYBODY. You make up your own mind or you might live to regret it.
Trust your intuition, your gut, and your conscience. They are there to PROTECT you from harm's way.
Don't ever for a moment think you're "being nice" by pretending to be someone's friend and then turning around and talking behind that person's back about something you're not even sure is true, but you're going around passing off as though it's fact. That is cruel, heartless, malicious, and mean. You're not being nice, so don't fool yourself into thinking you are.
If a friend is trusting you with very personal problems and your friend is honest (ie. isn't lying to you about anything and legitimately needs help and needs someone to talk to), and you act like you're a good listener and you pretend to care, don't go and whine to all your friends about how all that person does is "complain" about life. Now, Mr/Mrs. Self-Righteous, what do you think you're doing? If you don't care, suggest ways that will actually help this person get help (ie. therapist, etc). If you don't want to listen, DON'T! Nobody is making you and the more you pretend to care, the more "misery" you bring upon yourself.
The moral of the story to this:
Don't trust the "Gossip Train". You go to that innocent person and find out the facts. The only reason the gossip train people don't want you to talk to the innocent party (who HAS NO IDEA WHAT IS GOING ON, MIND YOU) about it is because they don't want you (the people who blindly trust them) to find out that they're liars who like to make stuff up for entertainment since they get some kind of twisted enjoyment out of it. They're probably just incredibly lonely people who let their imaginations go wild. I understand if you're a young person, still trying to figure out how to deal with your imagination, and stuff like that, but if you're an adult and still play this, you need to seriously grow up. If you have a problem with this, you need to go get help. Find out if you have a personality disorder or something, but don't excuse yourself and make yourself out to be the victim when you're the one lying