A mother, together with a male colleague, turned her two children against their father during divorce proceedings, so much so that their 15-year-old daughter publicly alleged that her father had sexually abused her and her younger brother.

But these allegations were unfounded, and the woman was found to have breached court orders by involving her children in the acrimonious divorce, in which she and her children accused the father of being a "mega-evolved sexual fetishist womanising pervert".

In judgment documents released this week, High Court Judge Debbie Ong said a parent has a responsibility to facilitate a child's relationship with the other parent.

"While children will have their own opinions and make their own decisions especially as they mature, parents cannot disclaim all responsibility for their actions," she said.

Justice Ong, in the grounds for her decision in the case, said the current state of affairs could largely be traced back to the colleague's role in the family.

The colleague had moved into the couple's home after the woman was diagnosed with breast cancer in October 2016, several months after divorce proceedings began in April that year. The woman's colleague claimed to be able to heal her tumours, despite having no medical training, and she paid him $15,000 a month to "remove" them.

The father grew concerned for his son and daughter, aged nine and 15 now, after he learnt of a claim made by the woman in February 2018 that the colleague had performed a "home mastectomy" on her. There were suggestions that the children were present at, or at least aware of, the "surgeries".

The father applied to take over care and control of the children in the interim, which a district judge granted.

The wife appealed against this decision to the High Court.

Justice Ong eventually ruled that the children were to be under her care and control, but reserved harsh words for the mother.

"What was especially troubling was the extent to which the wife and (her colleague) embroiled the children in the conflict," said Justice Ong, noting that the children's affidavits, which were drafted by the colleague, were "greatly disturbing". They "echoed biblical references and phrases" and allegations by the woman and her colleague in their own affidavits.

The children were highly resistant to their father after the appeal, and they went back to their mother a day after they were placed in their father's care in November 2018.

Justice Ong then ordered that they be placed in a home temporarily. The children returned to their mother about a month later and have continued to live with her since.

In June and July last year, the daughter posted the sexual assault allegations on her social media accounts. Along with her brother, they were interviewed by at least one online news outlet with their mother present.

The daughter also made a police report "confessing" that she and her brother were solely responsible for the posts and interview.

But the mother admitted that the police report was an attempt to absolve her from any responsibility, said Justice Ong.

"The wife had relentlessly polarised them against the husband to such an extent that any repair of their relationship with their father was not practically feasible," said Justice Ong.

The mother had informed her children of material in court proceedings and actively allowed her colleague to manipulate the children against their father, she added.

The woman thus breached a court order which prohibited her and the father from involving the children in the litigation.

Justice Ong sentenced the wife to one week's jail for contempt of court. She also issued a final order for the children to be in the mother's care and control, as it was not in their welfare to be isolated from her.

The woman is in ill health and separation is highly distressing for the children, Justice Ong said. The woman was diagnosed with stage four breast cancer in September 2018.

However, the mother should support access of the children to their father, she said. In the light of the mother's ill-health, the children should be able to rely on their father, she added.

The mother, who objected against a fine as she said money was better spent on the children, is appealing against the jail sentence.