Im with everyone else here IGNORE IGNORE IGNORE ..BUT if this wife is not contacting you more than once then you need to answer the phone and just tell her "I'm sorry this is a private number, please do not contact me again" and hang up. If she continues to call from that or other numbers then yes, I would contact him and tell him to sort his fucking home situation out and to keep me the hell out of it. At the end of the day its not your fault, its a situation of his making for not being careful with your number, imagine the song and dance that would be made should someone on your end start phoning him and saying "i know you fucked my girlfriend" or something similar?it would be all over the bloody internet with you being named and shamed probably.
I have had a couple of calls like this and I just told them sorry, it must have been a wrong number and then hung up. I did have one keep calling back shouting so I sent her a text telling her i have no idea who or what she is talking about but if she continued to harass me, a stranger, then I would contact the police?the calls stopped. Its not your problem x