Iris Robinson, the Northern Ireland MP who called gays an “abomination”, has announced she is standing down from politics due to depression.

Robinson, the Democratic Unionist MP for Strangford and wife of Northern Ireland’s first minister, Peter Robinson, released a statement yesterday saying she could no longer meet the demands of her job.

The 60-year-old was labelled a bigot for a series of outbursts last year in which she made offensive comments about homosexuality.

In 2008, she told the Belfast Telegraph that homosexuality was “comparable” to paedophilia. She also told a radio show that homosexuality was a mental illness and could be “cured”. Robinson escaped a police prosecution for the comments.

In the statement, she said: “Over the years, I have undergone a long series of operations and, though I have never talked about it publicly, I have also battled against serious bouts of depression.

“Only those who have faced similar challenges in life will know the ordeal faced by those who are profoundly depressed, and the distress caused to those around them as they grapple with personality-changing illness. One in four of the population struggle with mental illnesses at one level or another, yet few talk about it openly.

“The stress and strain of public life comes at a cost and my health has suffered. Regrettably, I have concluded, after considering the matter over Christmas and discussing it with Peter, who has always been most supportive and caring, that I can no longer maintain the high standard of service I require of myself, meet the demands of office and cope with the pressures of public life, without my health deteriorating further.”

Robinson and her husband were exposed in the expenses scandal for claiming almost £600,000 a year in salaries and expenses.

The couple earned six salaries between them and employed four family members as staff, the News of the World reported.

She earned £63,291 for her position as an MP, £24,296 as an Assembly member and as chairwoman of its health and social services committee and £9,550 as a councillor for the Castlereagh borough in Northern Ireland.

Her husband was found to earn £63,291 as MP for East Belfast, £71,434 for his role as First Minister plus a third of the £43,101 salary for being an Assembly member because he is also an MP.

The Democratic Unionist Party was said to be shocked by her resignation, with close allies unaware of her plans to leave.

She is expected to leave her Assembly position soon but will probably continue as MP for Strangford until a general election.