Karen Danczuk gave evidence at Manchester Crown Court where Michael Burke, 38, was convicted of a series of sex attacks.
Mrs Danczuk, 33, told the jury she was regularly molested by Burke in the family home from between the ages of six or seven until she was 15 or 16.
Her abuse can be reported for the first time after Mrs Danczuk waived her right to anonymity by speaking publicly after her brother’s conviction.
Burke, a “controlling and violent” man, denied 15 counts of rape, one attempted rape and one indecent assault against his sister and two other women, spanning an 18-year period from 1992 to 2010.
But after a three-week trial, the jury found him guilty on Wednesday of eight counts of rape and another serious sexual offence against three women, including three counts of rape against his sister between 1992 and 1994.
He was cleared of nine other serious sexual offences.
Mrs Danczuk initially revealed she had been abused, without naming her attacker, in an interview in February last year. In a newspaper interview yesterday after Burke’s conviction, she described her brother as a “monster”, adding: “He is sick, I hope he rots in hell.”
During the trial she gave evidence from behind a curtain around the witness box, shielding her from the dock where her tormentor sat, often shaking his head in denial.
The mother of two told of her unconventional and unhappy childhood, growing up as one of five children in a terraced house in Middleton, near Rochdale.
Her mother Sue moved a boyfriend in while Mrs Danczuk’s father still lived at the house but had split from his wife.
Mrs Danczuk said the abuse “started out like it was a game, it was not so much an attack, it was, like, innocent”.
She said the abuse progressed to rape when she was 11 – on a weekly basis, usually on a Sunday evening, which was “bath night” - and continued until she was 16. The abuse “ruined” her schooling and she left education with “crap” qualifications, she said.
She was cross-examined over two days by Nigel Power QC, defending her brother, who asked why she went first to the papers before the police, asked if money was her motivation, and accused her of “attention seeking”.
She said: “To this day, I have grown up and fought my whole life to change my childhood. I decided I would come forward, that was my choice. Before I ever became famous I was seeking help, before I ever knew I would end up in the public eye.
“This idea that it is just attention, this has ruined my life. I have had a horrendous life, it’s a fact.
“This is why I have had help from doctors, because it’s a fact. Days when ... being dead makes more sense than being alive.”
Burke will be sentenced on 15 December.