Paris Hilton -- Sleeping with the Enemy

Paris Hilton has figured out a way to settle a nasty lawsuit with a lingerie company -- she's going into business with them ... TMZ has learned.

Le Bonitas -- an Italian lingerie company -- sued Paris last year, claiming the heiress dragged her heels in approving designs, costing them 200k. For her part, Paris countersued for $1.5 mil, which she says she was guaranteed in royalties.

Hilton is in NYC today, and we're told she met with company honchos in court for a mandatory settlement conference. Apparently, it worked, because we're told they struck a new deal for Paris to front the nighties, and the lawsuit will go bye-bye.

BTW ... this will be the 18th product line Paris is hocking, with a net value of $1 billion.