I think that sometimes you let something consume you so much to hide yourself in it. And maybe for her it was being "mom." But she forgot that she was not just mom, she was also a woman. And, I don't know your story or how it went down in your house, but perhaps being just mom was her way to walk on eggshells, so she put her woman-self away in hiding.

Then, when the divorce happened, it was like suddenly she's "free" of the marriage, so she dropped the whole mom thing. But she dropped it too much. That's just a theory.