Fairy tales, Santa, and shit loads of stuff was told to us as children that was not real. Eventually we understood that and accepted it. Such parental deception has its root since ancient times. The only question is, till when should the lies be told.
Nicki Adams, mother of 10-year-old little Belle, was in the grey area when she decided to get over with it. But the little child could take only so much and led her to write some rude notes, but so it happens, they turned out to be funny.
But she was not ready and couldn't handle the information well.
And BTW, he doesn't exist.