If you caught your best friends husband or wife with another person or knew that he or she was having an affair, would you tell your friend?

No, none of my business

Yup cause if that person is your friend and YOU are a good friend, you would say something.

yes i would because it would hurt inside bigtime allowin a friend to go through that stuff not knowin.!!!!

hell yeah, cause what kind of best friend are you if you dont have your bestfriends back? id want them to do the same for me.

Yep..I'd tell..because I'd want her to tell ME if it were MY man out doing it.

Best friend yes. All the books say, stay out of it.

Yes...Because my friend deserves to know the truth...It's up to him/her what they choose to do with the information after that..

depends if i were the one doing her. lol. honestly, it would depend on the situation.

People who cheat are worhtless anyways so telling wouldn't be hurting you anyways.

I was in this exact situation. I chose to tell my friend. She turned her back on me and sided with her husband who told her I was only telling her this because I "wanted" him. He continued to cheat on her and she finally caught him a couple of years later. She called me up and asked to meet for lunch. She regretted her choice to deny what she knew in her heart was true. We are still friends to this day.

Best friend? Yeah, I'd tell him, and I wouldn't have to think twice about it.

Today it is no longer acceptable to turn the other cheek. With AIDS and HIV and other deadly diseases rampant in this country, it is no longer just an issue of infidelity. It is an issue of life or death. Most couples do not use condoms with each other so anything one brings home will be given to the other.
If I so much as think my partner is having sex with anyone else I will leave. I am not going to take any chances with my life. I already have an incurable disease from one cheating partner so I will not give any chances to a cheater.
I will always tell if I know for a fact, or if I have enough evidence to suspect then I will tell the other what I know so far while also telling them that I do not have concrete evidence, yet.
I won't let any friend of mine go untold.

I agree with Bickle

And then the husband and wife reconcile, and BOTH end up despising you. It happened to me. Thanks to me telling a man about his wife's cheating, I ended up with SIX people who worshipped the ground they all wished I was buried under. From now on, I mind my business, and if anyone I know's cheating, tough s*** to them.

Remember:No good deed goes unpunished.

Props to Knoxman and AllSmiles for offering some firsthand experience, showing how complex this situation can be, when it comes to -real life-.

For me, of course it would depend on the situation. Sometimes timing is everything. Sometimes there are ways you can 'out' the truth without directly involving yourself.

Isn't it better if the cheater comes forward themselves, then if you just accuse them? Now I wouldn't use the word 'blackmail', but I would consider 'encouraging' the cheater to do the right thing themselves. Depending on their personal ethics/psychology.

My problem was that I was so shy and antisocial that my wife was the only real friend I ever had. If I had a best friend, hmm, good question.

yes- i would owe it to my friend to tell her

nurjoyce... you would tell her that he is a hoe? lol