NEW YORK (REUTERS) - France's former lady Carla Bruni said she was hurt by press comments calling her fat after the birth of her daughter and squashed rumors that she would leave her husband Nicolas Sarkozy after his failed re-election bid.

In an interview in Vanity Fair magazine published on Thursday, Ms Bruni admitted she is in therapy and said she felt vulnerable when she was 18kg overweight after giving birth at age 43 to her daughter, Giulia, who was born in 2011.

"They get really nasty. Nothing is out of bounds," Ms Bruni said about the press comments. "Having children when you are older is not easy."

Ms Bruni described rumours about her marriage as "crazy" and added that she never thought of leaving Mr Sarkozy after he lost the election in May. Power was one of the problems they had to face together, she added.

"Power is brutal, and you have to be very structured inside to cope with power without getting blown away," she told the magazine.

The singer-songwriter and former model, whose newest CD Carla Bruni, Little French Songs was released on April 1, said therapy helps her think clearly and is about taking responsibility.

"And I like this type of work because with aging, if there is no philosophy, there's no serenity, there's no wisdom and there's nothing but falling apart," she said.

Although Ms Bruni said her husband listens to her advice, she said it is not her choice whether her husband launches a political comeback.

A formal investigation of Mr Sarkozy opened in March into allegations that he took advantage of the mental frailty of 90-year-old L'Oreal heiress Liliane Bettencourt, France's richest woman, in 2007 to raise funds for his election campaign.

Mr Sarkozy has described the investigation as "unfair and unfounded".