Amie, 31, who allegedly suffered back injuries in the incident, is now taking legal action against her former boss. She revealed to Britain's News of the World newspaper: "Naomi 100 per cent needs to get help. She was incredibly mean to me and very cruel. "She would scream at me every day - in public places - in front of people I knew. It really didn't matter.
There was no pleasing her and no end to the humiliation and degradation I suffered. It was like, 'You're my personal punchbag.'"
Amie says she decided to quit when Naomi allegedly lost control after she booked "the wrong" hairdresser.
The PA had called up for the model's favourite stylist, who wasn't available, so booked another of her regular hairdressers instead, to come over to the house to help Naomi prepare for an event that evening.
But when the catwalk queen found out her usual stylist wasn't doing her hair, she reportedly started complaining loudly about how useless Amie was - prompting Amie to quit.
She revealed: "I walked in and told her, 'Naomi, stop. I've had it with you talking about me like this to people. I quit.'
"With that, Naomi comes screaming out of the bathroom, grabs my arm, pulls me round and flies into my face, spitting, 'You're going to stay and finish your job. You're responsible for this 'f**k up'."
Amie claims the model then attacked her and a doctor later filed a report saying the injuries could have occurred "no other way than traumatic incident."
Naomi's spokesperson, however, has denied the claims, saying: "She categorically denies wild accusations by Amie Castaldo."