I see the similarities in theme: control. Right now, W sees me as controlling in our M - definitely not the case, but I was unsupportive to a great extent regarding her distress/depression. It frustrated me over time to see her not getting better, choosing to work to exhaustion over the years, with little time/energy left for me.
I also made the error of trying to get her to admit MIL's problems and I did act in a way that suggested I feared W would become like MIL over time. Instead I should have emphasized her healthy differences and loved and focused on that about her.
It is time to be supportive and selfless in my interactions with her. She'll need such support in order to heal.
My W still has to dance mainly with MIL when they are at a dance together - very odd similarities here.