A wanna-be minister from Chicago was hit with a two-year prison sentence yesterday for blackmailing Yankees slugger Gary Sheffield over a video purportedly showing his wife having kinky sex with soul singer R. Kelly.

Derrick Mosley, 39, a self-styled Chicago community activist, demanded $20,000 to destroy the tape that he claimed showed Kelly having sex with DeLeon Richards-Sheffield long before she married the baseball star.

Mosley insisted he was only offering his services as paid "spiritual adviser" to Richards-Sheffield, 29, a gorgeous gospel singer who has acknowledged dating Kelly, 39.

"[She] needed to atone," he testified during his trial, which ended in a conviction on Nov. 14. "She needed to repent."

He asked for leniency, citing his "track record with the community."

But Mosley will likely be hit with more time when a federal judge sentences him for violating his probation stemming from an unrelated bank fraud case.

News of the supposed tape first surfaced in 2004 when Mosley contacted Sheffield and the Yankees offering to keep the X-rated antics under wraps for a price.

The minister negotiated for a couple of weeks with Sheffield's agent, who later called the FBI to report the extortion try.

Sheffield, 37, backed his wife, saying he had long known about her decade-old fling with Kelly, who has been accused of bedding underage girls and taping the encounters.

The star right fielder hit 34 home runs last season, his second year with the Bombers.