Oh Spy,
It sure feels as though you know what you don't like.
I don't like your mother either. Igggggghhhhhh.
I do like Katie's spunk, which I bet she inherited from you. (Only a spunky woman would give that priceless response you did: oh, must've been the environment I grew up in...) BRAVO.

I hope you'll just dig in and recognize that you have got a spunky daughter who is eager to love her own child and who clearly considers you part of their lives. I hope this is a chance for you to just take pure simple JOY in being a grandmother and put YOURSELF and KATIE and THE BABY above NMum.
Always and forevermore. Don't let her in. Don't let her in to manipulate and tarnish and ruin the joy.
She's had her turn. And she BLEW it.
I think you can find great happiness as a grandmother, because you'll be a wonderful one.
As to knowing what you like? If you couldn't find out before, now it is your time to go exploring.
Exploring life, and yourself. You can do it. Even if you're not sure what you'll find, there's a very interesting woman in there.
Hugs,
Hops