Jessica Simpson on Years of Weight Scrutiny: 'Those Headlines Can Stay with You a Lifetime'

As a young singer and breakout reality star in the late '90s, Jessica Simpson endured such intense scrutiny about her looks and weight that it often eclipsed any other news about her life. It's a topic she wrote about in her bestselling memoir Open Book, newly out in paperback.

In the newly released version, she includes a journal entry from 2009 when a concert appearance made headlines and put the attention into "hyper drive" for how she looked in "mom jeans."

At the time, she wrote, "Today my heart breaks because people says I'm fat."

"Why does the cruel opinion of this world get to me?" she continued in her diary. "Last week I read back to my journals from 1999 and I beat myself up about how fat I [was] before I even gave the world a chance to..."

Now 40 and a mom of three kids — Birdie Mae, 2, Maxwell Drew, 8½, and Ace Knute, 7½ — with husband Eric Johnson, Simpson reveals how she healed from the hurt and what she's learned from sharing her story.

"There is a wonderful movement for body positivity now and the response to that portion of my story has been overwhelmingly supportive," she tells PEOPLE. "I don't think people always realized that there was a human being, a beating heart and working eyes with actual feelings behind those headlines and that words can hurt and stay with you for a lifetime."

Looking back, Simpson says, "I spent so many years beating myself up for an unrealistic body standard that made me feel like a failure all of the time. I am still a work in progress when it comes to self-criticism but now I have the tools to quiet those voices in my head when they speak up."

And she adds, "I believe in my heart that a healthy body and a sound mind-body connection are what's truly important and help me accept imperfections as beauty."

It's a bittersweet moment, she writes as she rereads her journal entry from over 10 years ago. "I hate that I was treated as an object to be tossed around like a rag doll," she writes, "but I smile to see me talking to myself back and forth across all these years."

For more on Jessica Simpson, and what she's learned by sharing her life story, pick up the latest issue of this week's PEOPLE, on newsstands Friday.