A married former NFL player who now heads athletics at New Jersey’s priciest private school is engaged in a steamy “quid pro quo’’ affair with a much younger employee, explosive new court papers allege.

Feted ex-Minnesota Viking player and dad Sullivan “Tripp” Welborne, the 57-year-old dean of athletics at The Lawrenceville School outside of Princeton, created a top job for illicit paramour Nicole Stock, 38 — and threw in an ATV for her to ride around the tony campus, to boot, according to the Mercer County Superior Court lawsuit filed Friday.

“Welborne would spend gamedays riding around on Ms. Stock’s John Deere ATV,” the suit claims.

Karla Despinis and Richard Rienzo, two former longtime top employees of the elite boarding school, where tuition tops $80,000, filed the suit after they

See Full Page