text: should i tell his wife that he is cheating? a guy and girl at work are having an affair. he is married with children and the woman from work that he is cheating with is living with her boyfriend of 9 years.  they go to company get togethers and are all over each other.  i know the wife of the guy, and the boyfriend ot the girl, but i'm not really friends with either of them.  it kills me that these people are being made fools of.  next week at the company christmas party they are all going to be there.  should i tell the wife or boyfriend, or is it none of my business? he will deny it and you will be branded the big bad b***h who was trying to split up a happily married couple coz you fancy him yourself.  ....well thats what he will say anyway!!  you will have enemy's coming out of your ears love!  it's a prediciment all right, i personally would like to know if it was my husband cheating, and i'd hope that someone would tell me.  but don't do it face to face, write an anon letter to her telling her days they are together etc  (he may say he is working late) and company do dates that she should be coming to as his wife that way she can investigate more and she can catch him in the act.  good luck x