I told her I was uncomfortable with so many questions and then she stepped even closer to me and asked another question.
That does it for me. That is well beyond "nervous conversation." That is an aggressive move. It is a deliberate violation of boundaries.
I don't care if this woman has a mental illness, was abused as a child, or any of the familiar excuses. If she acts like this, I want nothing to do with her. Especially in a play group where other people's children may be exposed to this aggressive behavior.
I agree with JenJay that you should contact her former chapter, and find out if she had problems there - especially how they handled it, and if their methods were successful. If they say they were forced to cancel her membership, well, that's a good fact to help you stiffen your spine.
And, as Levee woman said - Don't JADE (Justify, Argue, Defend or Explain.) Just expel her. As PPs have suggested, warn the ones she called (and called and called) while you were unavailable, since she will doubtless harass them again.
Good luck, and good wishes! Remember the all-purpose, E-hell approved phrases:
"I'm afraid that will not be possible"
"I'm sorry, I am unable to fulfill that request"
and "No," which is
a complete sentence!