The 'story' has been around for 2 decades and isn't especially salacious, so why would the press have been waiting to pounce until now?
And of course he sold her private story. Just because you don't mention a person's name, that does not mean they can't be identified. It will have been quite easy for the press to track her down, which is very likely what happened, leaving her with little choice but to cooperate.
I thought Harry was engaged in some sort of campaign against the tabloids? Surely he must have known that would happen when he included a story like this? Did he really think the press he rails against from his California mansion would not have been doing detective work about this woman the moment the story came out? And that they would have no more concern for Sasha's privacy and dignity, and that of her family, than he did?
Or does Harry's 'brave stance' against the British media begin and end with himself and his wife?