Stories about using heroin, resorting to thievery and hanging with prostitutes have circulated around Natalie Cole for years. Now, in an exclusive excerpt from her new memoir, “Angel on My Shoulder,” which is to appear in the new issue of PEOPLE, the “Unforgettable” singer, 50, details what was, indeed, her life of crime and of drug abuse — and chronicles her remarkable comeback. (On Dec. 10, Cole will play herself on the NBC TV movie, “The Natalie Cole Story.”) She got into music as a child, into drugs in college and into the heavy stuff just as her recording career was taking off in the ’70s, her book reveals. “I was approached to write this book 10 years ago,” Cole tells PEOPLE, “which was a real bad idea.” She feared how her son, Robbie Yancy, now 23, would react, to say nothing of the response of her mother, Maria, who is 78 and the widow of the singing legend Nat “King” Cole. Still, says Cole, “When you reach 50, what you care about is being honest, being accurate, and being an example.” And where is Natalie with her life now? Sober since 1983, and, she says, serving the Lord. “Don’t give up,” the voice of experience says in her book. “God ain’t through with you yet.”