Vanessa Bryant on Thursday accused her mother of seeking to “extort a financial windfall” from her in the wake of her husband Kobe Bryant’s death by filing a lawsuit claiming she is owed years of back pay for working as an unpaid assistant.

The family feud ratcheted up after Sofia Urbieta Laine sued her 38-year-old daughter for financial support, alleging she worked for years as an unpaid “personal assistant and nanny” to the couple and that the Lakers legend had “promised to take care” of his mother-in-law for the rest of her days before his death in a helicopter crash Jan 26.

“Unfortunately, Kobe Bryant’s promise did not see the light of day as he is now deceased and Vanessa Bryant took each and every step she could to void and cancel all of Kobe’s promises,” the 48-page lawsuit alleges, saying Vanessa Bryant never intended to honor her late husband’s wishes.

That was the final straw for Bryant, who also lost her 13-year-old daughter Gianna in the Calabasas crash that killed nine people and remains the subject of a National Transportation Safety Board investigation.

In a statement, she wrote that her 68-year-old mother was trying to “extort a financial windfall from our family.” Bryant said she and her husband of nearly 20 years had supported her mother financially, allowing her to live in one of their properties near their Newport Coast home free of charge.

“She was a grandmother who was supported by me and her son-in-law at my request,” Bryant said. “She now wants to back charge me $96 per hour for supposedly working 12 hours a day for 18 years for watching her grandchildren. In reality, she only occasionally babysat my older girls when they were toddlers.”

Bryant said that she was a stay-at-home mom to her daughters Natalia, 17; Bianka, 4; Capri, 18 months, and Gianna. She wrote that the children for the most part in the last decade were at school or in sports and that her mother’s claims “are obviously false.” Vanessa Bryant said her mother had never been involved in any of her and Kobe Bryant’s businesses or finances.

Bryant said their relationship soured after she tried to make peace with her mother.

“Earlier this year, I was looking for a new home for her and, a week later, she went on television and gave an interview disparaging our family and making false accusations while living rent-free in a gated apartment complex in Newport Coast,” she said.

In that interview with Univision, Sofia Laine alleged she was forced out of her home by her daughter and was made to return a luxury car. “She told me, ‘I need you to get out of the house,’ ” Laine said on “El Gordo y la Flaca.”

Bryant said the interview was “beyond hurtful.”

“Even after that betrayal, I was willing to provide my mother with monthly support for the rest of her life, and that wasn’t good enough. She, instead, contacted me through intermediaries — contrary to what she claims, my phone number hasn’t changed — and demanded $5 million, a house and a Mercedes SUV.”

Vanessa Bryant inherited control of an estate valued at as much as $600 million after Kobe Bryant’s death, according to financial experts.

She said she won’t give in to the “false and absurd claims” and demands.

“She has no regard for how this is affecting my children and me,” Bryant said. She added that her mother wants to live off her for the rest of her life while still collecting alimony from a 2004 divorce.

“My husband and I have never discouraged or kept her from providing for herself,” Bryant said.