not know the half of it
US /nɑt noʊ ðə hæf əv ɪt/
UK /nɑt noʊ ðə hæf əv ɪt/

1.
non sapere nemmeno la metà, non conoscere tutti i dettagli
to not know the full extent or all the details of a situation, especially one that is more serious or complicated than it appears
:
•
You think my job is tough? You don't know the half of it!
Pensi che il mio lavoro sia difficile? Non sai nemmeno la metà!
•
She's been through a lot, but her friends don't know the half of it.
Ha passato molto, ma i suoi amici non sanno nemmeno la metà.