Watch: Hilary Duff slams book publisher for releasing Aaron Carter's unfinished biography
The Lizzie McGuire star, 35, was in a relationship with Carter when they were teenagers.
The singer died at the weekend and Ballast Books is set to release his unfinished memoir, which is thought to be entitled Aaron Carter: An Incomplete Story Of An Incomplete Life.
Duff told DailyMail.com: 'It’s really sad that within a week of Aaron’s death, there’s a publisher that seems to be recklessly pushing a book out to capitalise on this tragedy without taking appropriate time or care to fact check the validity of his work.
"To water down Aaron’s life story to what seems to be unverified click-bait for profit is disgusting.
"In no way do I condone shedding any light on what is so obviously an uninformed, heartless, money grab."
Days after Carter died at the age of 34, a post on Ballast Books' Facebook page said: "Aaron Carter was a kind, gentle, talented soul not without his demons.
"He was so excited about telling his story, and we worked many hours on his book. Sadly, we’ll never have a chance to finish it.
"I feel I owe it to him to release the parts we did complete during sporadic work over 3 + years."
After his death, Duff paid tribute with a moving post on Instagram.
"For Aaron - I'm deeply sorry that life was so hard for you and that you had to struggle in front of the whole world," she posted.
"You had a charm that was absolutely effervescent … boy did my teenage self love you deeply.
"Sending love to your family at this time. Rest easy."
A spokesperson for Ballast told Yahoo: "Aaron Carter hired me to help him tell the world his story.
Read more: Hilary Duff leads tributes to Aaron Carter
"That story, while tragically cut short, was filled with good and bad. His life was far from pretty, and understandably certain people in the public eye don’t want some of the stories Aaron tells in his book to come to light.
"That doesn’t make them any less true or newsworthy. Aaron had a right - as we all do - to tell his story."
The spokesperson said the book was "cathartic" for Carter and that he hoped it would help those struggling with addiction and mental illness, adding: "I hope and believe it will do that."