.
I’m probably the worst person to give advice about mental health problems as my usual answer (just in my head) is “FFS pull yourself together”, but in this instance I feel able to give an opinion (rather than advice).
I suspect that the attraction is that they share a common problem and can empathise with each other in ways that anyone not similarly afflicted just can’t.
You say:- “the thought of my wife being away from me is filling me with dread”. Could this woman not use a hotel near to you and then your wife has no need to be away for long? Could you go along for their meeting?
This is a difficult one…
Has there been concern with the content of the conversations so far. Is your wife displaying any negative behaviours before after calls.
What is you worse fear.
What has your wife established from these calls. Does she actually feel she knows this person. Well enough to invite her. Has your wife see actual photos of this person.
Is there anyway you could make contact with the mental health forum. Because of confidentially I not sure how much you could ask.