Speaking outside his London home, Stephen Quinn appealed for his wife Kimberly, who is ill in hospital, to be left alone.
“She is not the greatest sinner this country has produced,” he said.
“It’s not really fair to keep on saying that ‘Oh my God, it’s terrible’, or whatever. We must have a sense of humanity, fairness, justice and reasonableness.
“It’s not right to keep attacking her about access and things like that.
“The issue really is that when Kimberly has her next child in February and when she can be rational, together and reasonable, we will deal with this.”
Mr Blunkett and the 44-year-old publisher of the Spectator magazine began their three-year affair just three months after she married Mr Quinn, managing director of Vogue.
Mr Blunkett was warned that he risked the health of Ms Quinn and her unborn child if he continued to fight for access to the children he says he has fathered. She is currently being treated in a London hospital where she is suffering from exhaustion and stress brought on by the publicity.
Mr Quinn, who was brought up in an orphanage in Thomastown, Co Kilkenny, said his wife was very distressed that her former Filipino nanny, Leoncia Casalme, had told her story to the media.
The 60-year-old said Ms Casalme was a born-again Christian and had promised the family she would not speak to the press.
“We treated her well, we treated her generously, we don’t like the fact she might have been paid by the newspapers to talk to them,” he said outside his home off Park Lane.
However, Mr Quinn said he did not feel betrayed by Ms Casalme and had made no attempts to contact her.
“It’s nonsense to say ‘she said this or something that’, it’s just tittle-tattle really and it’s hurtful, it’s damaging to her (my wife) when her health is quite frail.”
The call follows a Daily Mail newspaper report in which Ms Casalme gave her side of the story and said Mr Blunkett must have become involved in the process which led to the granting of her visa at a later stage than he had previously admitted.
Mr Quinn added that his wife was upset that she had been criticised by the nanny in the newspaper report.
“Can I just emphasise that Luc looked after William brilliantly, she was a terrific nanny and she loved the child but she’s a born-again Christian, she shouldn’t criticise the mother,” he told reporters.