Juliet Adebowale also spoke of her sorrow for the fusilier’s family, saying: “We’ve both lost a son.”
Michael Adebowale, 22, and Michael Adebolajo, 29, murdered the young soldier near Woolwich Barracks on 22 May. They will be sentenced in the new year.
Ms Adebowale, 52, a former probation officer, said her son had adopted extreme Muslim views only seven weeks before the killing when he met Adebolajo during a march.
She said her son – raised as a Christian – had been a shy boy who was bullied at school, and became a Muslim at 17 to protect himself from local gangs after he witnessed a friend being murdered. But he was drawn into extremism, and his mother was so concerned she befriended people at the mosque he attended so she could to speak with its imam.
She told a newspaper: “They said not to worry, it would be OK. Then I had the shock of my life in May when that harrowing act took place with that older man. It was so out of character, he was very vulnerable. When people are vulnerable, the evil ones will lure them.
“He had known Adebolajo since they went on a march at the end of March. I still can’t comprehend what happened, what got into his head. The extremism is tearing us apart.
“That poor, poor family have lost a son – but so have I.”
She said her son been on suicide watch since having psychotic episodes in which he saw “Christian angels” trying to lure him back from Islam.