Might be the perfect opportunity to text the OM's wife nicely with some carefully worded niceties that I mentioned before and then asking if she recognizes the following phone number that's been calling your wife's cell phone at {give approximate times and dates ]. Mention you were encouraged because the phone calls between OM's cell phone and your wife's had stopped for several weeks but these calls made you suspicious and that's the only reason for the text (you are seemingly respecting her apparent wish to not communicate unless it's important in a calm fashion).
You MIGHT end up losing this source of monitoring your wife but you really can't reconcile while they work together anyway. Her leaving that job (or OM leaving) just has to happen. There's no way you can be expected to sit around trusting her at that job when you know OM is around. It's unfair to you and unfair for you to be expected to tolerate it. It's got to be a firm boundary. I think she'll only leave the job if the affair is actually over so it's a pretty solid litmus test. Hopefully this recent contact is just some closure contact. Closure contacts [censored] and is completely stupid, unreasonable and hurtful but it's hopefully them just checking in with each other, how the lying is going for OM and TRYING to end it versus secret affair bliss.
They might think you've key logged her phone versus having a copy of the bill still. Giving approximate times might help mislead them that you weren't looking at the bill. If you lose access, oh well, that's hours of your day not staring and refreshing a cell phone bill saved.
She may be buying his lies but when she questions him whether he's talked to your wife by phone and he denies it....she may realize she's being lied to and put the screws to OM harder.
The internet is 90% complaining and entitlement and I hate it because I deserve better!
