JUSTIN BIEBER's mom regrets putting her boy through the pain and heartache she wrote about in her memoirs, revealing there were parts of her new book he struggled to read.

Pattie Mallette, who was 19 when the Baby singer was born, has opened up about her troubled past - including details she had kept from Bieber - for Nowhere But Up: The Story of Justin Bieber's Mom.

And she admits there were chapters her son struggled with, stating, "I know reading the book was really hard for him. I know a few times he just had a really tough time getting through some of the chapters and I can't blame him."

The book details Mallette's past drug and alcohol addictions and her childhood sexual abuse.