What you described sounds a lot like a phenomenon called Hysterical Bonding. While it may not be related to an affair it is usually related to one. I know you don't believe that and I'm a random guy on the internet who is rather jaded and am making assumptions based on limited information.
Therapy for both of you is probably a good idea at this point. I'm surprised that Christie hasn't been by with the contact info for Michelle's team. A number of people (I wasn't one) have found them helpful. Therapy together might not be productive as each of you have to get your heads straight before you can figure things out as a couple.
I would suggest giving her the space that she's asking for. If she's of a certain age menopause can certainly play havoc with a woman's thinking and emotions. Don't suggest that yourself though - I know from painful personal experience how that turned out But she may want to see her MD to just make sure that everything is balanced.
She sounds very wrapped up in her work which I presume is high stress. Perhaps her therapist (not you!) may have some suggestions on how she can better manage the stress.
Good luck
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells
But she may want to see her MD to just make sure that everything is balanced.