Nancy Mack -- the wife of Red Hot Chili Peppers drummer Chad Smith and the woman who attacked Scott Baio -- is a crazy person which this pic clearly shows ... this according to Scott's wife.

Renee Baio is livid that her family is getting attacked on social media ... because she says the only villain is Nancy Mack, who berated Scott for his support of Trump at an elementary school function Saturday and then allegedly physically assaulted him.

One person called Renee "a white trash blonde" and another ... "oh no! the poor little baby boy got scared because a girl pointed a finger at him! You must feel so safe with such a macho man at home."

TMZ broke the story ... Scott filed a police report and cops are investigating the case as criminal battery.

Renee just tweeted, "I'm not sure why me, my husband or child is getting bashed. Scott & BB were the victims. I was a witness." She followed that up with a reference to the pic (above), saying "Does this look like a sane mother/lady 2 you?"