It's not defamation if what she has said is true. Even if she wrote what was told to her, it's still not defamation because there was no intent to harm Dr. Wong's character, only to ensure her elderly aunt was not being defrauded.

At this point if I were Dr. Wong or a friend, I'd tell the doctor to count his blessings that she's not being brought up on charges because if I was the OP, I'd tell my aunt or her health care proxy to request her medical records & then I'd report her to NYS along with the IRS. It's not up to me to say what happened but it's certainly up to the regulating bodies to investigate.