I know lying isn’t against the law. (Although I’m neither a legal nor medical professional.) I meant she would be deterred from suing because the extent of her lies would have to be aired in court, in public, in order to prove the nurse revealed information.

In the case you linked, the nurse posted information about a rare case (ergo easily identified) whereas in OP’s situation the publicly identifying information had already been revealed by the mother and the nurse didn’t specify any new facts about the case itself. She might still get in trouble but it’s less cut and dried than the case in your link. Imvho.