if he denies it and his wife isn't sure...

Tell his wife ot go to OM's PC and read his email.

If they have separate PC's he is likley not deleting the mail... if he refuses to let her, he's signed his death warrant.

if he lets her, she will find something.

But the BEST way to handle this is to find some evidence on YOUR END on YOUR pc and print that up and take it to their home.

Do NOT tell your wife you are doing this.

She will find out eventually, but you do NOT want to WARN her becuase SHE will tell HIM to ERASE his PC of all evidence.

You MUST HAVE his WIFE support you here. If she does NOT believe you that her HUSBAND is cheating on her then you have to convince her... it is a LOT harder to fight an affair if you don't have the support of the OAS (other abandoned spouse)

Do what you can to get proof before you show up at their home.