Have you read Michele's article on the WAW Syndrome?
Here are some of my personal views about a stitch such as yours. It's not a defense of the WAW, but just a POV that I hope might help somebody.
Whenever a mother is so "willing" to leave her children without even considering another option, I tend to think she's running away from how she feels in her daily role of wife and parent. They represent "burdens" and she wants out from under the weight of the M and motherhood.
If she's been a good mother in the past, then something has caused her to think she will be happier without being in the home and involve full-time with her children.....especially a child with special needs. Any child that requires more of us than what we think of as traditional care, can take a toll on some adults. So, I think she may be looking for escape.
She didn't just wake up one morning and was changed from the way she use to be. This has been in the works. Boredom, depression, exhaustion, unfulfilled expectations.....so many things can contribute to that emotional state that sets a person up to be vulnerable to the very thing your W seems to find herself.
Here's the problem with her connecting with OM. Whenever a woman is in an EA, she's fogged out of her mind with PEAS. She's high on fantasy. She can't be realistic about the future or responsibilities b/c the fantasy gets in her way of thinking correctly. And believe me, talks do not work! You can have a R talk and even feel better right then, but it doesn't fix her, and you'll find out that she's right back to the mindset of a WAW.
She may have started the old friendship with OM as a way of escaping her daily life....and then it developed into an EA. Of course, she should never have been connecting with him in the first place. She's living by her emotions. That's why she doesn't have a game plan.
Where does your special needs child stay when you are working?
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!