People who suffer from depression need understanding and support, but Iris Robinson has crossed a line with behaviour that cannot under any circumstances be condoned.

To enter into a relationship with Kirk McCambley, the vulnerable and bereaved 19-year-old son of her deceased friend, was not just "inappropriate", as her husband Peter called it in his emotional interview the day before the BBC's Spotlight programme revealed the sordid truth, it was manipulative and an abuse of power.

Robinson, whether suffering from depression or not, was at the time one of the North's most powerful politicians, revelling in that position, delighted to be feted as a glittering partner of her husband, DUP leader Peter Robinson. She was an assembly member, a member of parliament at Westminster, the glamorous centre of the Northern power nexus.

He was 19. His father, a butcher, had just died. The imbalance of power in the relationship is so huge it cannot be condoned under any circumstances. One can only imagine the outcry if a powerful man of Iris Robinson's age entered a sexual relationship with the daughter of a deceased family friend.

Such double standards, from a woman who outraged the gay community by calling homosexuality "an abomination", have rarely been equalled. The perverse mixture of religion and politics in the North, in which politicians seem to believe they are entitled to make moral pronouncements about matters of personal belief, is exposed for the thumping hypocrisy it is. Iris Robinson's political career is destroyed.

Peter Robinson's position is on a knife-edge. How much he knew, and when, is still unclear. He has denied categorically that he has any questions to answer on non-declaration of interests because the £50,000 his wife solicited from two property developer friends to set McCambley up in business was, he says, paid directly to the young man.

His call for an independent investigation by a senior counsel to decide whether he breached parliamentary and assembly rules gives him breathing space. Such an investigation might even exonerate him on procedural grounds.

But these events undermine the unbending "morality" on which so much of his politics is based, and he is both politically and personally damaged.