The 56-year-old celebrity, who played the superhero on the 1970s TV series, said she has been sober for nearly 10 years after being confronted by her husband, attorney Robert Altman, People magazine reported Friday.
"I needed help -- I begged God in heaven to help me figure this out," she said of her struggles with the affliction.
She said with the support of Altman and their children, Jessica, 17, and Jamie, 20, she was able to get the help she needed at a rehabilitation facility.
The actress said prior to her family's involvement, she had little problem keeping the secret from the rest of the world.
"I was so good at hiding it too," the mother-of-two said. "Brilliant."