Lisa Marie alleges that Burton used false pretenses to get her to accept a lesser sum when they broke up in 2001.
The couple had been together for 10 years and had agreed to combine their finances while living under the same roof, Marie alleged in court documents obtained by People magazine.
Marie alleges the split left her depressed and that Burton took advantage of that by having associates contact her to convince her to settle the matter quickly because she would supposedly have little chance of prevailing in court.
People said Thursday that Marie, who accepted a Jaguar and the couple's New York apartment, wants to scrap the agreement and be paid unspecified damages.
Celebrity Families of 2014 [PHOTOS]