PARIS - She was Picasso's forgotten wife, written out of history as a "neurotic", snobbish depressive who was a drag on the great artist.

But a new exhibition is shining a very different light on Olga Khokhlova, his first wife who he refused to divorce because he did not want to split his artworks and his vast wealth with her.

Drawing on previously unseen letters, photographs and films from the Picasso family's private archives, Olga emerges as a major influence on the greatest painter of the 20th century.

Picasso fell madly in love with the beautiful Russian ballerina in 1917 after seeing her dance in "Parade" by Sergei Diaghilev, Erik Satie and Jean Cocteau for which he had designed the set and the costumes.

The exhibition at the Picasso Museum in Paris -- the first ever devoted to Olga -- shows how she was his main model and muse throughout his classical period.First his view of her was carnal, but as time went by and his ardour cooled, he portrayed her as melancholic, often sitting or reading.Later as their marriage soured in the 1920s and 1930s, Olga is shown as "deformed" and contorted by pain and regret.

- 'Opens up his life' -

By then Picasso was leading a double life having become infatuated with a buxom 17-year-old French girl, Marie-Therese Walter, who he picked up in the street.In one telling photo taken by Picasso in his studio, the slim and elegant Olga is shot sitting on a chair behind which looms a nude of the voluptuous Marie-Therese who -- unbeknown to Olga -- had replaced her in his bed.

Olga's grandson Bernard Ruiz-Picasso told AFP that the family's letters and photos allow a "really fascinating study of the direct links between the artist, his work and what was influencing him at the time".

Picasso's friend and biographer, the British art historian Sir John Richardson -- who described Olga as "rather neurotic" -- has already called the trove "a revelation and absolutely astonishing. It opens up his life," he said.

Picasso has often been condemned as a macho misogynist, whose sex drive and selfishness left a trail of destruction behind him -- with Marie-Therese, his second wife Jacqueline Roque and a grandson all committing suicide.But curator Emilia Philippot said the documents show a more nuanced view of his relationship with Olga, with one home movie showing her plucking daisy petals and mouthing the words, "He loves me, he loves me not."

   - 'Very mysterious woman' -

"She is a very mysterious woman. In his portraits and photos of her she does not smile a lot... but when you see her in the films she is actually very joyous and girl-like. She's a dancer and she is always dressing up and being playful with the dogs."

Ruiz-Picasso said it emerged from her letters that Olga had good reason to be sad and preoccupied.Born in what is now Ukraine, her father -- a colonel in the Russian imperial army -- had disappeared in the chaos of the Bolshevik revolution.While she and Picasso were climbing the social ladder in Paris, her family was losing everything.

Picasso idealised Olga on canvas as the model of perfect motherhood after the birth of their son Paulo in 1921, but soon the relationship began to go wrong.

"She was known for her fits of jealousy and obviously there were some real tensions within the relationship," Philippot said.

"But I think Picasso had love and respect for her. He too was a prisoner of their situation, which he expressed in comparing himself to the Minotaur," the imprisoned mythological half-man half bull.The couple separated in 1935, but still financially dependent on him, "Olga had real trouble accepting the separation", Philippot added.

"She was very alone and she suffered a lot. After the war when Picasso settled in the south of France, Olga followed him, going from hotel to hotel, living out of her suitcase," while Paulo became his father's chauffeur.

"She would send Picasso little cards with photographs of Paulo and the grandchildren as if they were still a family."But Picasso "never replied to her letters" and wanted nothing of the reconciliation and conventional family life that Olga craved.

Dismissed as "mad" by many of Picasso's friends, she died from cancer in the French Mediterranean resort of Cannes in 1955. Four years later Picasso married Roque, who he painted obsessively until his death in 1973.The exhibition runs until September 3.-AFP