She waited until the school holidays so she could protect them as the news broke, putting her three children first as always.
How hard it must have been for the Prince and Princess of Wales – and their team – to endure the endless speculation and lurid conspiracy theories that have swirled for the past few weeks, knowing she was facing a cancer diagnosis.
Many of those responsible may now be feeling some remorse over the fun they'd had at her expense.
With her searingly moving and deeply personal video message, Kate, 42, set the record straight, speaking from the heart as she explained just what has been going on for her beloved family since her surgery on 16 January.
The timing was not, as some suggested, in reaction to the rumours, but entirely designed to land once she and Prince William had whisked Prince George, Princess Charlotte, and Prince Louis away for Easter, giving them a chance to shield them from the inevitable acres of news coverage.
It was also very much Kate's decision, I understand, to share her news once she and William were ready and had given their children time to process and understand the news, which came as "a real shock", says a royal source.
For the family, this is a fresh blow in a year that has so far dealt them plenty.
After the King and Sarah, Duchess of York, the Princess is the third member to share a cancer diagnosis within three months and, again, it has come as a bolt from the blue.
The news puts into context Prince William's determination to be at his wife's side and explains his absence from the memorial service to his godfather, former King Constantine of Greece, a move that triggered much of the speculation online.
© GettyIt means the Princess will not be back at work as expected after Easter, although we may see her attend the occasional event if she feels able to. Nor will she and her family join the royals at St George's Chapel for Easter Sunday, while William will continue to balance his official duties alongside his care and concern for his wife and children.
"The Firm" may be depleted in numbers right now, but the public will understand the need for Kate to focus on her health above all else.
I think it's important to underline the fact that she and her medical team expect her to make a full recovery, and she has an optimistic outlook and is feeling positive about her treatment.
With the King and Queen going through their own cancer experience and the tight-knit Middleton family rallying around them, the Waleses will be hugely supported.
And the outpouring of messages from the public and the wider world will no doubt give them further strength.
Meanwhile Kate's message will have struck a chord with so many families living through a cancer diagnosis. Her bravery in speaking out, while also reassuring others they "are not alone", will have brought comfort to so many.
