Mary Lou seeks to defend Adams over Mairia 'uncle' claims
Ms McDonald said she was unsure why her party leader sought to repeatedly say Ms Cahill was raped by her uncle during radio and newspaper interviews last weekend.
Speaking to the Irish Independent, Ms McDonald said she "assumed" Mr Adams was "pointing out that the alleged assailant was a member of the broader family".
"It's not about a tactic and please don't ever imagine that stating that somebody who has been abused or potentially abused in their family circle is to disregard the matter, it's nothing of the case. Most abuse happens in those circles," she said. Ms Cahill described Mr Adam's comments as "despicable" and insisted her rapist Martin Morris was not a blood relation but rather an uncle through marriage.
She said some of her extended family could take legal action and her mother is "distraught" fearing people might think it was one of her brothers who raped her daughter.
"The only family matter in relation to this is the large dysfunctional republican movement and their arrogance to think they had a right to investigate child sex abuse," she said.
Over the weekend, Mr Adams accused the media of failing to report the fact Ms Cahill was raped by her "uncle" and questioned why "all the fact" about the case had not been published.
"I have huge sympathy for victims of abuse. Incidentally, the man who abused her was her uncle, that doesn't make it any easier but I have yet to read that in your newspaper," Mr Adams told the 'Sunday Independent'.
Separately, the Belfast woman contacted RTÉ when Mr Adams said she was raped by her uncle during a live broadcast on Saturday afternoon, and asked for a statement to be called out on air.
RTÉ agreed to do this.
RTÉ decided not to put a recording of Mr Adams's comments, which were made on Claire Byrne's radio show, on the station's website.
His comments came the day after the publication of the Starmer Reports which severely criticised the courts' handling of Ms Cahill's abuse case.
Northern Ireland's director of public prosecutions (DPP) apologised to Ms Cahill and two other sex abuse victims for failing them. Ms Cahill's rapist was never prosecuted and is unlikely to face trial. When she first broke her silence, Mr Adams and Sinn Féin pointed out that her abuser had been through the court process.
Ms McDonald said Sinn Féin never sought to discredit Ms Cahill.
"At no stage did anyone in Sinn Féin seek to second guess the story, as she said, the facts of her life, because she is the person who experienced the abuse. If you check what has been said on the record Sinn Féin people were very sensitive and incredibly sympathetic to that awful experience," she said.
Ms Cahill said the record showed Sinn Féin tried to discredit her by pointing out that those people were found non-guilty but the Starmer Report had now "blown their arguments to bits".