Margarete, Prinzessin von Thurn und Taxis was born on 8 November 1909 at Château de Beloeil in Belgium. Her full name is Marguerite Marie Therese Eilsabeth Frederike Alexandrine Luise, Prinzessin von Thurn und Taxis. Princess Margarete is the sister of Prince Raimundo della Torre e Tasse, 2nd Duca di Castel Duino.
She is still alive and is 99 years old (her 100th birthday is in November). I’m not sure whether she can be considered Prince Gaetano’s widow as they had divorced in 1950 in France, 8 years before his death. Actually, they had first divorced in 1940 in Hungary, however after doubts were raised about the legality of divorce, they decided to give another chance to their marriage, before finally divorcing in 1950 (in France).
Their only daughter, Diana, was born in 1932.
Princess Margarete is the oldest-surviving Royal (at 99), ahead of Infanta Maria Adelaide of Portugal (who is 97) and Archduke Otto of Austria (who is 96, turning 97 in November).
She is also the 3rd oldest Royal in History, after the Princess Alice, Duchess of Gloucester (who was 102 at the time of her death) and Queen Elizabeth, the Queen Mother (who was 101 at the time of her death).
She currently resides in France, although occasional visits (or used to visit) Belgium and Italy.