I really have appreciated all the input. Thanks :)
To update: I haven't heard a peep from my family after my second round of telling my Mom to lay off the almost mandatory communication she was demanding. This is odd, but here's what I really want to share with all of you:
Before I stopped talking to my Mom, I would go to therapy and feel a horrible guilt - a feeling as if I was making my trauma up - that it it was a huge lie and betrayal. I couldn't experience my own personal reality without the voices of my Mom haunting and influencing me.
Now - after just a few weeks of not speaking with her, it's like a complete turnaround. My reality is mine. I can talk about the trauma completely from my own point of view, with no interference whatsoever in my mind from her and what I think she would say or think. A weight is lifted and there has been a bit a relief in my life. A babystep at least.
I sent her a mothers day card, and hope the separation is not a permanent thing. But what I did - it WAS the right decision for me.
Also - the support I received from the members of this forum were extremely helpful in bolstering my confidence to allow me to make such a move. Thank you, and thanks to those who created and maintain this resource.