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Dell Curry is accusing his estranged wife, Sonya, of cheating on him with a former NFL player -- and then lying to him about her extramarital affair.

Sonya Curry filed for divorce on June 14 in a North Carolina court. The couple accused each other of cheating throughout their 33-year marriage.

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In documents, obtained by TMZ Sports, Steph Curry's father says Sonya is, and has been, dating Steve Johnson -- a 6th-round pick in the 1988 NFL Draft.

Johnson, a 6-6, 245lb tight end, played just one season for the New England Patriots. He left the NFL after 2 seasons with a knee injury.

According to The Virginia Pilot, the father-of-three is president and owner of Johnson Commercial Development, one of the largest commercial developers in the southeastern United States.

The 56-year-old multi-millionaire serves on several charitable boards, including Niswonger Children’s Hospital Foundation where he serves as Honorary Co-Chair.

Click here to see a photo of Johnson.

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In court docs, Dell, left, says Sonya, right, "began her extramarital affair with Mr. Johnson during the marriage and prior to the date of separation, and she lied to [Dell] each time she cheated on him."

Dell said Sonya is actually living with Johnson in Tennessee, and he claims she should not be entitled to alimony because she violated her marital vows by committing adultery.

Sonya fired back that she's in a "dating relationship" with Johnson who treats her like a queen. She claims she lives alone in a modest apartment because Dell kicked her out of their home.

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Sonya is pictured 2nd from right with Dell, left, Ayesha Curry, 2nd from left, and Steph Curry.

The 55-year-old homemaker said her current relationship didn't begin until months after she and Dell, 57, quietly agreed to a legal separation.

She claimed it was actually Dell who was unfaithful to her by hooking up with multiple loose women during their marriage. And she put up with his cheating ways for the sake of their children.

Sonya says Dell's infidelity was known to her children and close friends, and that his cheating was basically an open secret.

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There are rumors that Steph, 33, convinced his mom to stay with his dad when she threatened to divorce him years ago.

Dell and Sonya married in 1988. In addition to Steph, they share son Seth Curry, 31, who plays for the Philadelphia 76ers, and daughter Sydel Curry, 26.