Jennette McCurdy felt "broken" by Ariana Grande on the set of 'Sam and Cat'

Writing in her memoir 'I'm Glad My Mom Died', she said: "What finally undid me was when Ariana came whistle-toning in with excitement because she had spent the previous evening playing charades at Tom Hanks's house. That was the moment I broke."

Meanwhile, the short film director alleges in the book that her late mother Debra - who died of cancer in 2013 - pushed her into showbusiness at a young age and can remember feeling that their relationship would improve once she had landed a starring role in 'iCarly' on Nickelodeon at the age of 14.

She writes: "Everything's going to be better. Mom will finally be happy. Her dream has come true."

The former child star also explained that her youth was "exploited" and while there may have been people around her with the "best intentions", they weren't always aware of what they were doing.

She said: "My whole childhood and adolescence were very exploited. It still gives my nervous system a reaction to say it. There were cases where people had the best intentions and maybe didn't know what they were doing. And also cases where they did - they knew exactly what they were doing."

According to the New York Times, Jennette also claims to have suffered indignities at the kids' TV network throughout the book such as being made to drink alcohol against her will but alleges that she was offered a sum of $300,000 by Nickelodeon to remain quiet about her experiences.

'I'm Glad My Mom Died' is due for release on August 9.