In Open Book, Simpson also wrote about her cousin, Sarah, dying in an accident when they were teenagers. Simpson's new essay reveals that Sarah's death made her question if she'd even survive after the book, which was the result of "two years of stillness and introspection," was released to the world.
"I declared that there were no more secrets," Simpson writes of her Open Book dedication to Sarah. "But there is one more secret I haven't shared: I thought that publishing a memoir meant that I was going to die."
Simpson writes that her fear of death post-book release "might sound ludicrous" to the public, but explains why the possibility was heavy on her mind.
"Sarah had recorded her life so beautifully in her journals, and her mother sharing them with her church community had made such an impact, that for decades I thought that was why God had called her home," Simpson writes. "She had fulfilled her purpose -- written the summation."
That belief was only reinforced as Simpson worked to write and release her memoir.
"I had felt Sarah so close to me as I wrote, her presence at my side becoming stronger and stronger leading up to the release of the book, that I thought she was there to take me home too," she shares.
Now, though, Simpson says she believes that feeling to be nothing more than fear.
"I realize now, that was fear trying to drown out Sarah’s inspiration to make good on my desire to live freely and openly. To dare," she writes. "It didn’t want me to hear what Sarah was really there to tell me: 'We’re just getting started.'"
Conquering her fears, Simpson writes, has been one of her main focuses throughout the last year, as she works to let them go "big and small, one by one" to get "where I need to go."
"If I want to lead myself into something greater than yesterday, I have to surrender the things that scare me and hold me back," she writes. "... We have to confront each demon, truly feel the emotions brought up and trace how they've wired our daily thoughts, judgments, and actions. Make friends with the things that scare us, but take away their power."
When ET's Rachel Smith spoke to Simpson in March, the singer opened up about how releasing her memoir helped her in her fear-quashing quest.
"To be honest and true to yourself... I feel like it makes just life, and choices, and everything so much easier, our relationships, even our reflection," she told ET. "... I feel like now since the memoir has been out I have never felt more of myself. It gave me permission to be who I am."