The Virgins of Venice by Gina Buonaguro

In sixteenth-century Venice, one young noblewoman dares to resist the choices made for her
Venice in 1509 is on the brink of war. The displeasure of Pope Julius II is a continuing threat to the republic, as is the barely contained fighting in the countryside. Amid this turmoil, noblewoman Justina Soranzo, just sixteen, hopes to make a rare love marriage with her sweetheart, Luca Cicogna. Her hopes are dashed when her father decides her younger sister, Rosa, will marry in a strategic alliance and Justina will be sent to the San Zaccaria convent, in the tradition of aristatic daughters. Lord Soranzo is not acting only to protect his family. It's well known that he is in debt to both his trading partners and the most infamous courtesan in the city, La Diamante, and the pressure is closing in.
After arriving at the convent, Justina takes solace in her aunt Livia, one of the nuns, and in the growing knowledge that all is not strictly devout at San...