Mr Johnson began donating sperm after arriving in New Zealand in May to work on Christchurch earthquake recovery. He created an online persona "chchbill" on unofficial websites for those seeking sperm donors.
The desire to have children followed his holding the first child born to Mrs Johnson's oldest daughter. He said he turned to sperm donations because Mrs Johnson had a hysterectomy two years before they married.
Mr Johnson, who could not be contacted, said at the time the desire to father a child was "a need that I have". "Reproduction and having children is as basic a human need as eating," he said in December.
His actions caused concerns in the fertility medicine community which has guidelines restricting donations to no more than four families and regulating donations to fertility clinics.
It has also led Mrs Johnson to campaign for a law change in the United States which would make it illegal for men in long-term relationships to donate sperm without their partner's knowledge.
Mr Johnson returned to Alabama in the United States after news broke in December of his activities. He left Alabama just after Easter to be in Christchurch for when the babies start arriving.
A candidate for the Republican nomination to be governor of the state in 2009, Mr Johnson campaigned on a political platform opposing gay marriage. A number of the women he donated to are in committed civil unions with gay partners.
Mrs Johnson said she had fought for five months to save her marriage but could not break her husband's fixation on the babies he had biologically fathered.
"He's back there now. He says he has a commitment to them. He says he created these children and he has a responsibility to them," she says.
"I said 'what about your commitment to your wife'. He walked out."
She said Mr Johnson had returned to work for Ceres NZ, the international disaster relief company where he was based when reports first emerged of his donations.
Mrs Johnson said after news of his secret life as a donor broke her husband flew back to Alabama to confess all.
"He doesn't really know how many pregnancies there are out there. Some women were so angry they didn't want to talk to him again."
She said he had told her he had donated sperm to women wanting children at least 50 times over a handful of months.
She said he had assured her the donations were non-sexual.
Inquiries by the Weekend Herald with the women found the donations happened with increased frequency as time went on. By the time he left New Zealand in December, Mr Johnson was donating on multiple occasions throughout most weeks before he returned home.
Mrs Johnson said on his return the couple sought counselling. She also visited a counsellors to try and find a way through the shock. "I don't think we had the honesty in our marriage I thought we had. Now, the trust is completely gone.
"I feel completely devalued. I have to pick up the pieces and move on. I need to focus on healing for my children and me."
She said before he left "he told me he is not going to stop".
"I said 'you're walking away from a good marriage and a strong family that is willing to come to forgiveness'."
Mrs Johnson said at best he could only have a "part-time" role in the lives of his children.
She said he had signed away his rights to the children but had an expectation he would be able to build a relationship.
She said Mr Johnson had planned on applying for residency so he could stay in New Zealand.
"He is obsessed with this. He doesn't want to stop."
Canterbury University professor Ken Daniels, an expert on assisted human reproduction, said those who donated outside fertility clinics were increasing the emotional and other dangers to the children they fathered because the support networks did not exist.
"The internet and Google has opened up this area in a way that no government can control."
