Three of Zephaniah Waks' 17 children were abused by employees of Jewish institution Yeshivah Melbourne as students of Yeshivah College, including prominent Jewish victims' advocate Manny Waks.

Mr Waks, who has been ostracised by the ultra Orthodox Chabad community after supporting Manny in going public with his story, likened the stigma associated with being a "moser" in the Jewish community to incest in general society "It's that bad," he told the Royal Commission into child sexual abuse on Tuesday.

Victims' families tearfully recounted to the commission how they had been shunned for reporting abuse to the police, which was seen as a breach of "mersirah" a religious rule preventing Jews from informing on other Jews to secular authorities.

Mr Waks said that the problems with mersirah were cultural, not legal.

While he understood the rule had been created due to the historical religious persecution of Jews: "In matters of life and death including child sexual abuse this rule must be broken, albeit with proper safeguards.

"If a religious community hides behind false ... or even real religious precepts to seriously harm people, especially children, I believe the state must interfere."

The Commission is examining major Jewish institutions Yeshivah Melbourne and Yeshiva Bondi's responses to abuse allegations against former employees David Cyprys, Daniel Hayman and David Kramer, and mersirah's role in preventing victims coming forward.

The wife of one of convicted sex offender David Cyprys' victims, known as AVC, said she had lost faith in orthodox Jewish leaders' response to child sexual abuse: "Our community has become a reincarnation of the Salem (witch trials in) Massachusetts of 1692, and the devil is everywhere."

"Under the watchful gaze of the Yechi Hamelech (long live the king messiah) sign, rabbis preach against mesirah ... preaching hellfire and damnation for those who have let the secular world in where they have failed," she said.

AVC said rumours spread about their family, who were blamed for unrelated events happening to other Jews as a result. Her children worried they were hated and they were all now ignored by people who were once close friends.

"We are being screwed once more by the adolescent, self-serving and callous response of the community. at a time when support and love are needed we are facing hate and vitriol. No one cares about what is right they only care for expediency."

Mr Waks said when he was first told one of his sons had been abused by his former friend Kramer in 1993, he did not report it to police for fear of breaching mersirah. Kramer, who was sent on a Yeshivah-funded trip to Israel days after parents claimed he had abused children, was later sentenced to three years in prison for indecent assault and an indecent act against a child under 16.

Rabbi Zvi Telsner labelled Mr Waks a "moser" or informer behind his back for breaching the rule, he said, which under Jewish law meant other Jews could legitimately kill him.

This prevented other victims and their parents from coming forward and isolated those who did, with supporters too afraid to befriend him publicly because it might negatively affect their livelihoods in the Yeshivah Centre and their children's ability to marry.

Mr Waks felt forced to move to Israel with his wife, unable to attend most synagogues in Melbourne. Even in Israel he had to "be careful" not to associate with "Anglos" or the Chabad community there.

For a family whose lives once fell entirely within the Melbourne Chabad community "It felt like we were suddenly reduced to nothing and had lost all our friends," he said, breaking down.

According to Mr Waks, Rabbi Telsner directed a sermon about rabbis' power to ex-communicate worshippers to Mr Waks' family shortly after The Age first reported Manny's story in 2011.

Mr Waks said he was also twice assaulted in front of a full synagogue by a man who accused his children of "making trouble" for his own children. The man threatened to make one of Mr Waks' other sons "suffer".

Mr Waks also said he was refused the honour of being given a reading of the Torah in the synagogue when he was entitled to on his birthday.