Wives and girlfriend happen. The best thing for you to do is either..
A. Block his number
B. Dont answer The calls
C. If you do end up talking to the wife, don't say anything of substance. Give her a sales pitch for something totally boring. If she mentions oh2, play dumb.

This is not the first wife on oh too and it will definitely not be last. Don't let the paranoia take over, just take the safety measures that you always do.