Marie was nicknamed "Heroin of Gaeta" because of her courageous behaviour during the siege of the Gaeta fortress where she and her husband had fled after their neapolitan throne had been overthrown by Garibaldi's troops. The young queen became the soul of the resistance to the enemy, encouraging her husband's soldiers during the battle and nursing the wounded men under bullets and bombs. When the opposing forces asked her for the location of her home in Gaeta so as not to drop bombs on it she staunchly refused to give it. However Gaeta was lost and the now ex-royal couple took refuge in Rome where Marie had a love affair with a young belgian count, Armand de Lawayss. She secretely gave birth to an illegitimate daughter by Armand, called Daisy, in the Ursulines Convent in Augsburg in 1862. Her daughter by King Francesco, Cristina-Pia, died in Rome, aged only 3 or 4 months. For all I know, King Francesco was not homosexual, only a shy and extremely religious man, totally inhibited. He suffered from a phimosis which prevented sexual relationships.
Marie and Francesco's first years of marriage had been somewhat unhappy but later they reached some kind of understanding. They often visited her bavarian relatives in Germany but mostly lived in France (Paris & nearby Saint Mandé) and England where the young queen loved to hunt. It is actually she who invited her sister Elisabeth to join in and the empress so enjoyed herself that she made several others trips to England during the following years (much to Kaiser Franz Josef's distress and to the Vienna population's anger). However on one of these occasion Marie behaved unfairly toward her elder sister, spreading rumours about a love affair between the empress and Bay Middleton, en english horseman. She even told Kronprinz Rudolf, Sisi's son, about it which caused a row and estranged the 2 women.
Marie never forgave the House of Savoy for "stealing" her throne and is said to have plotted against them. She strongly opposed the projected marriage between her grand-niece princess Marie-José of Belgium and the heir to the italian throne Umberto, telling the young girl that if she married him, she would bitterly regret it and never be happy.
She spent her last years with her sister Mathilde in Munich where she died in 1925.