"Sometimes I feel like the one who is on the sidelines who has missed life itself," he wrote in one of his letters, chronicled in the Anthony Sampson biography "Mandela."
Mandela's release at the age of 76 led to negotiations that ended decades of racist white rule and set the stage for his presidency in South Africa's first democratic elections in 1994.
He served one term and then retired from political life in 1999, establishing the Nelson Mandela Foundation to fight poverty, AIDS and illiteracy in Africa. Since then, his life story has been a beacon to the world.
But Mandela's personal life was fraught with operatic tragedy.
When then-president de Klerk released him from Victor Verster prison Feb. 11, 1990, Mandela learned that his wife of 30 years had been unfaithful.
His oldest and favorite son, Thembi, never once visited him in prison, and Mandela only learned about his death in a car accident by telegram in 1969.
He married his first wife, Evelyn Mase, in 1944, but they divorced after arguments over his political involvement. They had four children, a daughter who died in infancy and two sons who perished in adulthood. Mase died in 2005.
But it was his second wife, Winnie Madikizela-Mandela, who caused him crushing humiliation, taking a lover at her home while he was confined to prison.
"It was real agony for him, genuinely horrible," "Mandela" researcher James Sanders said. "She was a big superstar and she had a lover in her house."
Their long, passionate romance began in 1957. She was a social worker and 16 years younger than the 38-year-old activist. Marrying a year later, the couple radiated both political and sexual energy. They had two girls.
Madikizela-Mandela was never allowed to assume the role of first lady because of her infidelities.
Still active in South African politics, she is held in both awe as the "Mother of the Nation" and contempt, for her alleged involvement in human rights abuses, including the torture and murder of 14-year-old activist Stompie Moeketsi in 1989.
But Mandela loved again, capping his 80th birthday in 1998 with his marriage to Graca Machel, the 52-year-old widow of Mozambican president Samora Machel, who died in a 1986 plane crash.
"Late in my life, I am blooming like a flower because of the love and support she has given me," Mandela said of the child rights activist, whom he met shortly after he was released from prison.
"If I could say in a very modest way that's what I was able to give him back," Machel, a noted campaigner for children's rights, said in a 1998 interview. "I'm happy that in his sunset years I was able to be there for him. And he is there for me."
Mandela's three marriages have produced 18 grandchildren and six great-grandchildren.
One of them, Mbuso, was particularly close to Mandela -- the same boy who toured the presidential palace as a toddler later attended a high-level state dinner as a 4-year-old in pajamas.
"Mbuso had been in Durban City and was expecting his grandfather to put on his pajamas and sleep with him that night," said Mandela's friend Bizos. "Instead, Nelson was dressed in a suit."
"Mbuso started crying, 'Grandpa, are you going to go out again?' So he brought him," Bizos said. "It didn't matter what the occasion was, the child got preference."
At the same time, Mandela relished his role as an international superstar.