Dumisani Rebombo is no ordinary advocate for women's rights in South Africa. He is a rapist.

He is a rapist who sought out his victim two decades after his brutal act to ask for forgiveness.

He is all this in a nation where sexual assault has become so common that a woman in South Africa is more likely to be raped than learn to read.

Sexual assaults rarely shock anyone anymore, though a video of a brutal gang rape of a mentally disabled teenager went viral on the Internet last month. That touched a nerve.

As the young suspects face their day in court, Rebombo spoke with CNN to tell his own story -- an extraordinary tale of violence, redemption and determination to change things in his homeland.

Rebombo was 15 when he raped.

The boys in his village of Blinkwater taunted him because he didn't herd cattle and instead went home to help his sisters. He didn't have a girlfriend.

"Sissy," the village boys jeered, and challenged him to prove his manhood.

The way to do that was by having sex. Forced sex.

Rebombo had refused until that day, when he gave in to peer pressure. He recounts what happened in a quiet, steady tone.

Two of his friends picked out a girl. They said she thought she was smarter than the boys; she didn't date anyone.

Rebombo and his friends would set her straight.

"I was afraid because I'd never had sex before," Rebombo says.

At 5 o'clock in the evening, he met his friends, drank beer, smoked marijuana.

Then it started. The first boy raped her; then the second. She was screaming. It was Rebombo's turn.

After it was over, he felt terrible, wracked with guilt and scared that his parents would find out. He says he never gave a thought about how the victim was feeling.

"It's because when the environment accepts that behavior as a norm, you don't pay to much attention to it," he says.

The South African police say there were 66,196 cases of rape in 2010-2011. But many believe that number is much higher because many rapes go unreported.

The girl Rebombo raped never reported what happened and Rebombo was never charged. She never even spoke about it with anyone. She was too scared of the consequences, Rebombo says.

A Medical Research Council study found that 28 percent of men in South Africa reported having perpetrated rape; three-quarters of first-time rapists are like Rebombo -- under the age of 20.

"This violence, there is violence elsewhere in the world, but you don't see the staggering numbers of rapes that are seen here in South Africa," Rebombo says.

He is glad, he adds, that South Africans are finally talking about it.

Asking for forgiveness

Rebombo eventually left his village in Limpopo Province and joined first a religious organization and later an aid agency. He learned about respecting others but strangely, he says, he rarely thought about the girl he raped.

Years passed and Rebombo started working at a gender equality organization, where he spoke with rape victims about the different emotional stages they went through. That's when he thought about his victim. She did not even have an opportunity to seek counseling. Rebombo began feeling the need to make amends for his actions.