Carl Niehaus, a former anti-apartheid activist, ANC member, theologian and businessman has written an open letter to his 11-year-old daughter, telling her of his gang rape in prison in 1983, the night before he was found guilty of high treason and sentenced to 15 years in jail.
In his blog on Litnet.co.za, Niehaus recounted how a white prison warder, who apparently saw him as a traitor to his fellow Afrikaners, took him from his single cell in Diepkloof Prison in Pretoria and put him in another cell with 20 common criminals.
The former ambassador to the Netherlands was quoted in Afrikaans-language newspaper Die Burger as saying he could not remember precisely how many men had raped him, but he guessed it was more than 20.
"It went on and on and on," he said.
Niehaus wrote: "When you are bleeding from your ears and mouth, and you can only see a blur, and you are thrown in a small room where the walls, the floor and the roof are all sloping and skew and blinding lights flash hour after hour with screeching sounds being bombarded at you, until the only thing you can do is to scream louder and throw yourself against the walls to feel more pain, because the pain is something to hold on to, something to prevent you from falling down a dark abyss of insanity."
Niehaus knew who the warder was, but didn't want to name him "and ruin his life".
The following morning in court he could not walk without help. He was convicted of plotting to blow up a gas factory in Johannesburg.
Niehaus said although his wounds had healed, the psychological pain stayed with him. He nevertheless never regretted fighting against apartheid.
In his open letter, Niehaus said he was able to talk about his painful experiences thanks largely to his wife, Linda Thango, whom he married in 2002 after his divorce from his partner in the struggle, Jansie Niehaus.
The blog sparked praise from some internet users and disbelief from others.
The Litnet content manager, Melt Myburgh, said he believed Niehaus's blog would play an important role in the healing process that people like him had to go through.
"May our society one day be free from these types of nightmares," Myburgh wrote.
During imprisonment from 1983 until 1991, Niehaus earned bachelors and honours degrees in theology summa cum laude from the University of South Africa (Unisa).
He also received the Unisa senate medal as best post-graduate student.
After his release, he was made a member of the ANC's negotiation commission and was elected to the provincial executive council of the ANC in what is now Gauteng.
During his career, he has acted as President Nelson Mandela's spokesperson, became a partner in accountants Deloitte & Touche, and the chief executive of Rhema Church.
He has also written three books.