TV  icon FLORENCE HENDERSON is revealing her deepest, darkest secrets in a riveting new book – and after its fall release, fans will never look at her the same, say sources familiar with her autobiography.

The Brady Bunch star says she was living a lie with her public image as a bubbly, smiling sitcom mom. In real life, Florence actually was a tightly wound ball of fears, who fell into a severe depression while struggling to cope with a troubled marriage.

The still untitled memoir, published by the Hachette Book Group, hits stores in September.

"Florence reveals that her private life was a far cry from that of happy-go-lucky suburban mom Carol Brady, who came into TV viewers’ homes each week," a publishing insider told The ENQUIRER. "Behind the scenes she was terribly unhappy."

As the youngest of 10 children, raised in rural Indiana poverty, "Florence learned to sing for her supper, clean houses and work in the fields," said the insider.

"She supplemented the pittance earned by her father, a tobacco sharecropper, during the Depression."

By age 2, the budding child performer had an amazing repertoire of 50 songs, and by 17, she was beginning her climb to Broadway stardom, overcoming crippling stage fright.

But in her early 20s, Florence faced a frightening personal and career crisis when she nearly went deaf. Doctors discovered a deformed bone in her middle ear, which required surgery.

Florence later married theatrical manager Ira Bernstein and had four children.

"But it was a loveless marriage and she was terribly lonely," revealed the insider.

"She suffered agonizing postpartum depressions, and their careers kept them apart for long stretches."

Despite a fear of flying, the actress commuted between Hollywood and her New York family home during the Brady Bunch years (1969-1974), but her home life crumbled after she learned her husband was unfaithful – and she divorced him after 29 years of marriage.

"She finally found the love of her life in hypnotherapist John Kappas," said the insider."

With his help, she overcame her fears and phobias and actually trained to become a hypnotherapist.

"They were married for a blissful 15 years until his death, and she says to this day that their time together was the happiest in her life."