When a Manhattan socialite lost the key to the safe in her Paris pied-à-terre, she channeled her inner burglar and had the lockbox blowtorched open — allegedly destroying millions of dollars in modern masterpieces.

Tracey Hejailan’s estranged husband, Maurice Alain Amon, lays out the bizarre incident in papers filed Thursday in Manhattan Supreme Court in a fight over their $25 million art collection.

He says the hatchet job left the artwork and “sumptuous furnishings” that decorate the $7 million Rue du Cirque apartment covered in “toxic dust” — and that’s why she can’t have nice things.

Amon said Hejailan misplaced her key on Saturday, Feb. 4, and when his security chief told her she’d have to wait until Monday for a replacement, she took matters into her own hands. “She had people enter the apartment and cut a large hole in the safe with what appears to be a cutting torch,” Amon says in court papers.

A local bailiff investigated Feb. 8 and described the scene in a report.

“The safe emitted a burnt odor. There was rubble on the floor and a great quantity of dust everywhere,” according to the court papers. Amon later had an art expert survey the damage.

“I saw with my naked eye that the majority of the contemporary art, by artists such as Jean-Michel Basquiat, Damien Hirst, Richard Prince, Gerhard Richter, Cy Twombly and Andy Warhol, were covered by the fine concrete dust generated by breaking into the safe,” Christopher Lucien says in the Manhattan court statement.

He determined that the modern pieces are embedded with dust and may be impossible to clean.

The housekeeper, who first found the apartment in an “indescribable state” on Feb. 6, vacuumed up most of the dust. But curtains, suede wall coverings and a mink-covered sofa are still cloaked in soot, the filing says.

It’s unclear what Hejailan needed out of the lockbox, but she left just one item behind before leaving the country — a gold wedding band.

Her lawyer, Gerard Riso, did not return messages seeking comment. Amon’s attorney, Peter Bronstein, declined to comment.

Amon is the heir to a Swiss currency-printing fortune. He gripes in the suit that he gave his socialite spouse tens of millions of dollars in gifts over their eight-year marriage, including their $22 million Fifth Avenue pad, two London investment properties, a Swiss chalet, a boat, a Ferrari and $10 million in jewelry.