The teenage schoolgirl abducted and sexually abused by teacher Jeremy Forrest has cut ties with her family and moved out of her parents' home, her mother said in an emotional victim impact statement.
The victims' mother said she felt that she had "failed as a parent" and had her daughter's childhood "robbed from me". Her daughter, she said, had aimed all her anger at her mother.
"I feel the (daughter) I knew is dead and it upsets me beyond words," she said.
Forrest has been jailed for five and a half years after he groomed the 15-year-old pupil for sex then abducted her when he was about to be exposed.
He pleaded guilty to five charges of sexual activity with a child as he appeared at Lewes Crown Court to be sentenced for child abduction.
The 30-year-old Maths teacher, who took the pupil to France to avoid arrest, was not originally charged with sex offences for legal reasons linked to his extradition.
The now 16-year-old, who cannot be named for legal reasons, was not in court for the sentencing hearing but had been there yesterday when Forrest was convicted.
The mother, who was sitting in the public galley, said: "I feel completely useless most of the time, I feel like I have failed as a parent as I cannot understand how someone could do this to my child and I had no idea."
She said that her other children had suffered and they had had to move home.
She continued: "I feel like the worst mother in the world, whatever anyone else says it doesn't matter.
"Someone has got my child and I never saw it coming and never saw it as it was happening.
"I feel like part of (her) childhood has been robbed from me, the last day at school, dressing her up in a party dress for the school prom, all taken from us."
She added: "My relationship will never be the same again, she is aiming all her anger at me, that she has to give evidence in court.
"Somehow that is all my fault, she thinks she cannot trust me again and she has gone to live elsewhere."
The teen wrote a series of online messages aimed at Forrest during the trial, according to the Daily Mail, promising "I'll always be waiting for you".
Earlier she had written on her birthday: "Realising that 16 feels exactly the same as being 15. Oh, the irony!"