Ignore and block. That takes a LOT of nerve on that woman's part.
Or a completely different view of the situation, or a different set of boundaries or appropriateness.
This woman may feel a sense of kinship with your mom, because they were both treated badly because of your dad's "habits." The world is full of ex-wives or ex-girlfriends who end up sort of banded together. They loved and were hurt by the same man.
So that may be what's driving her--and it isn't nasty or evil. But it's distasteful.
So I agree with the "ignore and block" advice.