The former TOWIE star, 24, has kept a dignified silence about her ex-boyfriend since they split up last year, but has now chosen to open up in her new book, Secrets And Lies.
In extracts from her upcoming autobiography which have been published in The Sun On Sunday, Sam describes Joey as immature and delusional.
She writes: "If delusion was an Olympic sport, Joey would have a gold medal. He is like Peter Pan, frozen in time and unable to handle anything bad or real.
"He plays on the 'Little Boy Lost' act and has always had a real skill for twisting things round to suit him because he has never really been made to grow up and take responsibility for himself.
"That's why we had to break up, for the sake of my sanity. I hoped it would end in marriage and children, but in the end I didn't know who he was any more."
Celebrity Big Brother star Sam, who dated Joey on and off for about four years, also opens up about Joey's brief relationship with Amy Willerton after meeting on I'm A Celebrity... Get Me Out Of Here!
She then admits she ended her on-off relationship with Joey by text message, where she accused him of being "paranoid".
She adds: "It was only once I finally knew the relationship was over that I could see it for what it had really been. Made up of some good bits, but by and large fairly toxic."
Sam has since moved on with property developer Paul Day, while Joey recently confirmed he had a new girlfriend.
The upcoming autobiography Secrets And Lies: The Truth Behind The Headlines is available to buy on 23 April.
It begins from where her last tell-all memoir Living Life The Essex Way: TOWIE And Me left off in 2012.
Joey's own autobiography Being Reem was released last year.
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