. She visited Britain this week in order to draw international attention to her students' situation.
"Even if I had given up education, there wouldn't have been a positive result. So I was adamant and determined. But I also used to pray and hope that my son would come alive and safe to my home."
During the period that 17-year-old Hamayoon was in captivity, his father and uncles would listen for any reports of unclaimed dead bodies. On several occasions, they exhumed unidentified corpses, searching for Hamayoon.
After 15 months, Hamayoon was strangled. His body, riddled with bullets, was dumped in the desert, where seasonal floods washed it into a nomads' camp.
"Even today, my other children have psychological problems as a result of what happened to my son," Ms Wafa said. "But that atrocity did not affect my determination to stand up to the people who oppose education, and to stand up for this country.
"I will not give up, because education is so important. It's through literacy and education that we can eradicate poverty and eliminate other social problems in our country."
Ms Wafa has used her time in Britain to meet politicians and union officials. She also addressed students at Quintin Kynaston Community Academy in North London, recounting the difficulties that she and her students have had to endure.
"Some of the girls have suffered acid attacks on their faces," she said. "In other cases, girls have been poisoned through water given to them at school. Even after the murder of my son, I still face threats: roadside bombs on my way to school.
"Insecurity is a big issue facing girls' education. But when a mother gives birth to a child, whether it's a male or a female, that's a human being. More people need to have an awareness of that."
"Education is a massive privilege," said 17-year-old student Tierney Fauch, after Ms Wafa's talk. "We should have an appreciation of it."
Asiila Sharif, aged 13, agreed. "Sometimes in lessons, you don't pay attention and you're wasting time," she said. "You're just wasting that opportunity."
Ms Wafa's father was a strong believer in the importance of education, and his daughter received both secular and Islamic schooling. He asked her to pledge that she would help to promote education for other girls, whatever career she pursued.
She began teaching in a refugee camp in Pakistan. Later, she chose to move to warlord-ruled Laghman province. "I always tell students, if you live in an area where you have to put on a veil, do not disagree with that," she said. "Wearing the burka is not the problem; illiteracy is the problem. Comply with it, wear the burka and the veil, so that you can one day become college educated."
Many of Ms Wafa's students have now gone on to higher education and good jobs. Several are teachers and doctors: when she had an operation recently, two former students were among the medical staff looking after her.
"Normally, when I go to an office, I come across one of my students in a position of authority," she said. "That makes me proud. It gives me pride and energy to continue my work."