Dell Curry says his estranged wife, Sonya, cheated on him with a former New England Patriots tight end ... and then lied to him about it.
It's all spelled out in court docs, obtained by TMZ Sports, in which Steph Curry's father says Sonya is, and has been, dating Steven Johnson -- a 6th-round pick in the 1988 NFL Draft.
In the docs, Dell says Sonya "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.