Paris (AFP) - France's scorned former first lady Valerie Trierweiler is set to lift the lid on her tumultuous relationship with the president on Thursday in what could prove an explosive memoir.Trierweiler, a journalist, was dumped unceremoniously by Francois Hollande in January after a magazine revealed his affair with actress Julie Gayet, and has since remained broadly silent about an event she once said had felt like falling "from a skyscraper."But the 49-year-old had all along been secretly writing a book about her years-long relationship with the Socialist leader, which comes out on Thursday and does not "spare" Hollande, according to parliamentary channel LCP which broke the news."Everything I write is true," she writes on the cover of the book, called "Thank You For This Moment" and unveiled in Paris-Match, a glossy magazine for which she used to be a political reporter and still contributes to."At the Elysee (presidential palace), I sometimes felt as if I was on a story.