The Nelson Mandela Foundation has expressed its sorrow at the passing of Winnie Madikizela-Mandela, who died after a long illness, at the age of 81, on Monday.Madikizela-Mandela, an anti-apartheid struggle icon, was also the former wife of late president Nelson Mandela."All South Africans are indebted to Mama Winnie, whether they acknowledge it or not," said Foundation chairperson Professor Njabulo Ndebele.Madikizela-Mandela was regularly detained, tortured and placed under house arrest by the apartheid regime."From the witness of her life, we knew we could stand tall; we knew also we could falter and stumble. Either condition was an affirmation of life. Her cry was our cry, and in 2018 we can say we did triumph," said Ndebele."We will miss her. And our country will miss her. Hamba kahle, Mama."