An off-duty NYPD detective on his way to work was killed in a car crash when a wrong-way driver rammed into his vehicle in Westchester early Friday — and the cop’s widow said he wasn’t even supposed to be on the road for several more hours.

“May would’ve made 30 years that we’ve been together,” said Det. Paul Duncan’s grieving wife Rechelle who said she was unknowingly stuck in the traffic caused by her husband’s fatal wreck. “I know no one can believe that because I look so young,” she joked through her tears.

Rechelle said her husband had to work an unusually early shift Friday and did not see him before he left their home in Hartsdale sometime before 4 a.m.

“His usual routine was an 8 [a.m.] to 4 [p.m.],” she said “He would drop my daughter at school in the city.”

“Today he had to be there super early so it was a different routine.”

The accident happened around 4 a.m. on the Sprain Brook Parkway between Route 100B, and the Heatherdell Road overpass in Greenburgh, cops said.

Duncan, 46, was a 17 year NYPD veteran who worked for the Internal Affairs Bureau’s narcotics team making undercover buy-and-busts and trying to gain intel on dirty cops.

The head on impact was so severe, it launched the cop’s Honda Pilot over the highway’s outer guardrail and came to rest in a snow bank, pinning him inside. He was dead at the scene.

Investigators noticed his NYPD placard still inside the vehicle, the sources said.

“Really, there was no man better than him and I say that in all honesty,” the cop’s wife said. “He was a good good person. He was a good husband. He was a good dad. He was a good detective, a good son, nephew, son in law and we’re going to miss him terribly. ”

The man who rammed into him, Efren Moreno, 53, was in a Honda Civic, that rolled at least once before coming to rest in the highway’s center lane.

A team of first responders had to use the jaws of life to cut each of the men out of their vehicles, according to a police source, who added that both men were believed to have been wearing seatbelts.

Moreano was found stinking of booze when investigators came upon him, sources said. A bag of marijuana was also found inside the car.

“He was going the wrong way at 4 a.m. and there was marijuana in his car,” said a source, “but its unknown how impaired or intoxicated he may have been.”

Investigators from the New York State Police believe Moreano began his doomed journey when he entered the southbound lane by way of an exit ramp and began traveling north for roughly 1.5 to 2 miles.

Several witness called police to alert them to the wrong way driver, a source said.

“One of the witness called us and said she swerved and almost got struck by the wrong way car,” said the source. “She swerved to avoid him.”

“We had just dispatched troopers to be on the lookout for a wrong way vehicle on the Sprain [Brook Parkway],” he continued. “The accident occurred within less than a minute probably.”

Both Duncan and Moreano were believed to be traveling at around 55 to 60 miles per hour at the time of the crash, which took place on a curve, giving the cop little time to react.

Moreno was put in a medically induced coma at Westchester County Medical Center and suffered a fractured leg, chest injuries and internal bleeding. Police took a blood sample that will be tested to determine whether he had been drinking prior to the crash.

Duncan was traveling in the right direction when he was killed, cops said.

All lanes were reopened at about 8:45 a.m.