I never believed that! You had to be living under a rock with no media, no TV at all not to have heard if the Monarchy, Princess Diana, etc.
She has a picture in front of the palace when she was younger, and I read an article about her writing about Princess Kate on her own blog.
From the start she wanted to marry him for fame/money/position and thought Harry was dumb enough to believe that. I guess she wanted to make him believe that she was interested in him as a person, not for his position.
Many people blame Harry for not teaching her the truth, but it takes just a little brains and a google search to know that the Monarchy is all about hierarchy, they were never going to upstage William and Kate. They were never going to be more important than them. England is not the only country with a Monarchy, there are plenty of other examples. So, from the beginning she was planning her exit; therefore, writing a journal of everything that was happening when she moved in.
She knew she could manipulate Harry into doing whatever she wanted since the guy seems not to be smart.
She wanted half in / half out so she could make money and be a Hollywood start, not to be living a quiet life. They also wanted to be sponsored by the RF, that's why half in. Weren't they already applying to copyright Sussex Royal into a lot of merchandise y the time of the announcement?