Justin Bieber opened up about reading his mother's memoir for the first time.

According to Contact Music, Bieber admitted he was shocked by what his mother went through in her life when he read "Nowhere But Up: The Story of Justin Bieber's Mom," and found reading it "tough."

''Yeah, it was a lot for me to hear. But I'm older now. When I was younger, my mum never told me any of this stuff. It was definitely hard reading those stories, but I'm supportive of her writing the book. It's cool,'' he told Macleans.ca.

Pattie Mallete, Bieber's mom, wrote about drug addiction, sexual abuse at a young age, and abort in her memoir, which was published on Sept. 18 by Baker Publishing Group.

Mallete's mother Diane and stepfather Bruce Dale were also shocked by some of the incidents in the book, which they were both unaware of.

''There are three sides to every story. There's one side, the other side, and then there's the truth," Dale said.

The 288-page book is described:

Most people only know her as Justin Bieber's mom, but Pattie Mallette has had an incredible journey of her own. Many people have heard of her son's rags to riches triumph. A few know she was a teen mom who had to overcome a drug and alcohol addiction. Even fewer know the rest of her story. 

Now, for the first time in detail, Pattie shares with the world the story of a girl who felt abandoned and unloved. Of a teenager who made poor choices. Of a young woman who attempted suicide and could hardly bear to believe that God would ever care for her. One who messed up, got pregnant, and got a second chance. Every reader will find themselves somewhere in Pattie's painful journey of redemption. They will be encouraged by her example that what was once broken can become whole.

Pattie's story will inspire readers to believe that even in the darkest of places, there's always hope. For those who feel unlovable, there's always love. And for those who believe they're a lost cause, there's always room for another chance.

"I'm really grateful to God and to all the people who have surrounded me and loved me," she told USA Today. "I always wanted to write a book about my story. I wanted to be as vulnerable as I could, so that young girls who have been through similar things could relate. I pretty much bared my soul. It definitely furthered my healing process."

[READ EXCERPT HERE]

Readers can purchase "Nowhere But Up" on Amazon for $12.86.