"It's all a blur, it was surreal," she says on VH1's Behind the Music: Jennifer Hudson on Monday night. "It was like I was outside of myself."
As her very public nightmare unfolded, the Oscar-winning actress says she went into seclusion.
"For almost two weeks straight . . . [I was] inside one room with just family and friends coming in and out," she says. "I prayed when I'd get up in the morning and prayed before I laid down at night."
Hudson barely addressed the murders until the 2009 Grammys, where she performed a poignant, moving rendition of "You Pulled Me Through."
"I was definitely thinking of my family when I was singing that song," she says. "I could hear my brother in my head, like, 'Jennifer, you need to kill this, you need to get up and do it.' I knew he would be disappointed if I didn't do it justice."
Today, "I feel like I've lived about three or four different lives," she says, adding that her 11-month-old son David (with her fiancé David Otunga) has helped her heal.
Little David, "reminds me of my nephew," says Hudson, and he also helps her remember her mother. "In so many ways I channel her because she was such a great mom."
Her son, she adds, "makes me feel like the most special person on earth. I want him to get the same love and the same upbringing my mother gave us."