Ambreen Naeem appears in a new BBC2 documentary, In The Face Of Terror, airing Tuesday night in the UK.
She watched the livestream in an attempt to locate her husband Naeem Rashid, 50, and son Talha, 21.
"As soon as I saw the video I saw Naeem," she told the documentary, according to the Daily Mail.
"He tried to tackle the terrorist; I saw the determination in his eyes and the expression of bravery on his face and I loved him more than I've always loved him."
Brenton Tarrant, 29, pleaded guilty to killing 51 people in the attacks. He was sentenced to life imprisonment without parole - the first time in New Zealand's history the sentence has been imposed – in August.
Naeem rushed at the gunman until he was within feet of the man who fired four shots at him at point-blank range.
He rushed at him once more and the gunman fell to one knee before shooting Naeem again, killing him.
Naeem, a teacher, was among nine Pakistanis killed during the mosque shootings on March 15 last year.
It was a phone call from her sister and later a friend which alerted Ambreen to the attacks.
The friend had suggested she watch the video as she was still yet to hear from her husband and son.
"When my sister called me she told me 'There's been a shooting in the mosque and a lot of people have died."
"Where are Naeem and Talha?" She responded.
After a few attempts to contact her family members by phone, Ambreen decided to check the hospital injured list, neither of their names were there.
"I still had hope."
But by 9pm that night, she could not wait any longer and mustered the courage to watch the livestream.
In the documentary, Ambreen is seen visiting a specially-constructed cemetery in Christchurch, visiting the graves of her loved ones.
"It [the video] was something unimaginable."
"I lost half of my family because of some person's hate. I will see him in heaven. It's just the body, he's always alive in our memories."
Pakistan honoured Naeem posthumously with an award for bravery.