"Yes, I have filed for divorce," the 45-year-old Oscar-winner tells the magazine. "I'm sad and I am scared.
The actress also announced she is now the mother of Louis Bardo Bullock, 3½-month-old boy born in New Orleans.
"He's just perfect, I can't even describe him any other way," she says. "It's like he's always been a part of our lives."
Bullock says she and James, 41, began the adoption process four years ago and brought Louis home in January, but they opted to keep their new addition a secret until after the Oscars. The actress tells the magazine she is finalizing the adoption as a single parent.
Ten days after Bullock won her best actress award for her role in The Blind Side, James became the center of a cheating scandal in which several women claimed to have had affairs with him — namely tattoo model Michelle "Bombshell" McGee.
The Monster Garage star, who publically apologized to Bullock and his three kids for his "poor judgment" recently returned home from a treatment facility to deal with "personal issues," according to People.