The King's Daughter by Sandra Worth
Book Blurb: Seventeen-year-old Elizabeth of York trusts that her beloved father’s dying wish has left England in the hands of a just and deserving ruler. But upon the rise of Richard of Gloucester, Elizabeth’s family experiences one devastation after another: her late father is exposed as a bigamist, she and her siblings are branded bastards, and her brothers are taken into the new king’s custody, then reportedly killed.
But one fateful night leads Elizabeth to question her prejudices. Through the eyes of Richard’s ailing queen she sees a man worthy of respect and undying adoration. His dedication to his people inspires a forbidden love and ultimately gives her the courage to accept her destiny, marry Henry Tudor, and become Queen. While her soul may secretly belong to another, her heart belongs to England.
If you happen to have a copy that you want to sell... :3 I'm looking out for it.