Aged only fifteen, she became the bride of Alfonso XI, King of
          Castile and Leon. However, the king's affections were elsewhere and,
          after giving birth to two sons, she was abandoned. Twenty-two years
          later after the king's death, on her orders the king's mistress was
          arrested and subsequently strangled.
               The new king, her son Pedro I, at only sixteen had already formed
          an attachment but was forced to accept Blanche de Bourbon as his
          bride. However, only two days after the marriage he left her and
          returned to his mistress, Maria de Padilla. His mother, the Queen
          Mother, gave her support to a league of nobles who forced the king to
          dismiss all Maria de Padilla's relations and supporters.
               However, in 1355 the king had four of the principal leaguers
          stabbed and bludgeoned to death at Toro in the presence of his mother,
          whose garments were spattered with their blood and brains. Horrified,
          she retired to her native Portugal where the discovery of her own
          indulgence in a licentious affaire caused her father to have her
          poisoned.
 

Source: Leo van de Pas