The DUP leader also disclosed that Iris Robinson tried to kill herself last year after he discovered her relationship with a prominent Ulster businessman. The East Belfast MP insisted, however, that he would stay in the job as first minister while seeking to rebuild his marriage.
Just before Christmas Iris Robinson announced that she was retiring from politics and public life owing to mental health issues. The Strangford MP was at the centre of controversy last year when she denounced homosexuality as an "abomination" which she said could be "cured" by psychiatry.
There had been speculation over the last 48 hours not only about their marriage but also Peter Robinson's future as first minister. In a press conference tonight at his east Belfast home to which only a handpicked group of broadcasters and journalists were invited, the first minister said he had forgiven his wife and stressed that he would not be resigning.
In two statements, Northern Ireland's "first family" spoke candidly about their marital difficulties. Although Iris Robinson was not at the press conference, the Strangford MP's statement said: "Over a year and a half ago I was involved in a relationship. It began completely innocently when I gave support to someone following a family death. I encouraged friends to assist him by providing financial support for a business venture.
"Regrettably, the relationship later developed into a brief affair. It had no emotional or lasting meaning but my actions have devastated my life and the lives of those around me."
In the study of his home, speaking emotionally, a gaunt Peter Robinson said: "My first knowledge of Iris's inappropriate relationship came about midnight on March 1 last year – the night she tried to take her own life. Each single morning since then I have asked for the strength to carry this burden. I admit that my immediate impulse was to walk away from my marriage. I felt betrayed after almost 40 years of being happily and closely bonded together.
"The circumstances I faced, however, caused me to take a different course. Iris, racked by guilt and regret, had attempted to take her own life and would certainly have been less likely to recover if I had left. Over time and on calmer reflection I set her inappropriate behaviour against 40 years of bringing up our children – often alone. "Forty years of selflessly giving me the space to pursue my beliefs; of facing public pressure for the stand that I was taking and having to live with the threats and dangers my position visited upon my family.
"Those were 40 years during which she supported me more than any person could reasonably have been expected to. Forty years where we walked the valley basin as well as the mountain paths — but most of all 40 years during which we shared a strong loving relationship. I determined that I could not walk away without making a genuine effort to see if my marriage could be saved. That is the road I am on. It is a road without guarantees but it is not without hope. I love my wife. I have always been faithful to her."
Before the developments, the first minister had not been seen in public since before Christmas. He came under fire for failing initially to issue a statement on the death of the former leader of Ireland's Catholics, Cahal Daly. Although he eventually did offer his public sympathy on the cardinal's death, Robinson did not attend Tuesday's funeral in Armagh city.
Up until this very public crisis in their marriage the Robinsons had been one of the best-known political double acts in British politics. Before she was elected in 2001, Iris Robinson worked at her husband's side for more than 25 years.
She stood by her husband when he served a short prison sentence in the Irish Republic after leading a loyalist "invasion" of a County Monaghan village in 1986. Robinson explained that the late night incursion into the southern village was to expose a "gaping hole" in border security.
To read more about this vicious homophobe, why not look at her wiki entry? Includes: "just as a murderer can be redeemed by the blood of Christ, so can a homosexual.... If anyone takes issue, they're taking issue with the word of God." Charming woman.