Gospel singer Cissy Houston has revealed dhe didn't learn the devastating news about her daughter Whitney until two hours after the tragic superstar was pronounced dead.

Whitney Houston was found unconscious and submerged in the bathtub of her Beverly Hilton Hotel suite in Los Angeles on the eve of the Grammy Awards last year (11Feb12).

Paramedics, who rushed to the scene, listed her time of death as 3:55pm, but her mum Cissy confesses she was one of the last to know of the tragedy, revealing she found out from her son Gary at around 6pm.

In her memoir, Remembering Whitney, she writes, "(A voice said), 'Oh, mommy! It's Nippy (Whitney's family nickname)! It's Nippy!' It was my son Gary on the line, and he was hysterical. (I said), 'Gary, what's wrong?' 'It's Nippy,' he said again. 'They found her!' 'Gary, what happened?' I snapped, frightened. 'You've got to tell me!' He just kept mumbling, 'Oh, Mommy,' until I finally said, 'Gary, is she dead?' And he said, 'Yes, Mommy. She's dead.' And that was the moment my whole world shattered."

But the 79 year old insists it took time for the tragedy to sink in.

In another excerpt, obtained by People magazine, she writes, "(Those first days) I believe I was in shock, because I'd be sitting in my chair, crushed under a burden of grief, and suddenly I'd hear someone screaming. And then I would realize those screams were coming from me. Since my daughter died, I've struggled with so many things.

"I'm still so angry - at Nippy, at the world, at myself. Should I have done things differently? She was a person whose life and voice touched millions of people. I'm as proud as any mother could be about her daughter, but I would trade every last bit of it to have my baby back... I still wonder if I could have saved her somehow, but there's no book written on how to be a parent. You do the best you can."