"I couldn't stop crying that weekend, grieving for the life I'd had before," she said yesterday.
The mother of four is facebook's vice-president for Europe, the Middle East and Africa.
She bravely opened up about her incurable cancer on the social media network yesterday and in the Sunday Times yesterday.
She wrote on Facebook: "I often talk about how people can seize their own destiny, so it's tough to be reminded that there are things you can't control.
"Just over a year ago I was diagnosed with follicular lymphoma - a slow developing cancer of the white blood cells that's not rare and that has no cure. It is quite an unknown disease which is why I've decided to raise awareness by telling my story in the hope of driving research and a better understanding of it."
She was diagnosed with follicular lymphoma and has opted to "watch and wait" rather than undergo chemotherapy.
She also wrote in the 'Sunday Times' magazine yesterday: "I had a horrible two days trying to process it. It was worse that I didn't find out all in one go. I couldn't stop crying that weekend, grieving for the life I'd had before."
When she broke the news to her young children, they asked, "Are you going to die?"
"That's always the thought that comes into your head when you hear the word 'cancer'," she wrote. "It is not a conversation I could ever have imagined having with them, not even in my worst nightmares, until it hit me in the face. It was the hardest moment of my life."