Thanks all - to clarify:
a). I have no idea of what phone number she might use (besides his) so blocking etc. is no good
b). If she phones me, it will be because she's been to my website, via a link on an email to him - that's what I meant about not denying being a WG. She may also have cross-referenced with an entry in his phone book.
In other words, IF she phones me, she knows I'm a WG, and she knows I've seen her husband. I'm trying to ascertain how best to deal with that scenario for both his and my own sakes.
I considered trying to call him tomorrow, but I guess that might just add fuel to the fire?