Is this film based on a true story ? " contains spoilers" and horror

There is a lot of "bug" psychosis that end in someone dying,

Here is a true story then happened in Sydney Australia in the 1980's
A mother and her twenty something daughter, the Mother had the Psychosis,
they are is the shower together the Mother says there a Bug under you Skin {cheek} and says I'll grab a scalpel, and she starts digging, the Mother removed the daughter's whole face the she died in the shower,