I am processing it:

AesB,

I suspect that what has happened here is that her denial has triggered
the same emotions that get triggered when your family does the same:
insist that nothing you remember ever happened (those scars from a
knife would were always there, etc. etc. and we were always one big
happy family).

All you can do at this point is go back to believing in you, and
recognizing that others will do whatever they need to do to protect
themselves (mostly from themselves). She can't face seeing herself as
someone who would, in essence, cheat to get her state license and so she
insists it never happened. Protecting her self-image is far more
important to her than considering how her actions may affect you.
Family dynamic again.

Have to remind yourself: it's not about you. I like your hypothesis:
let's not XX and then I won't have to face her. Makes sense to
me. Now you just have to accept that you don't need to do that (avoid
her) because you are no longer the same person who did not say no to
her previously. If you so choose, when you see her you can let her
know how you are affected by her 'lack of memory' - and you don't have
to choose that if you don't wish. You just see her for what she is and
let her be. What she chooses to believe, or insist upon, does not
change who you are, or what actually happened.

So, once again - take back your power over you and don't give it to
people like her. She does not get to drive your life off the rails,
not any longer.

Wishing you a wonderful ... and productive ... day.

Love,
FM

"I hope I can tell her."