He was a millionaire rock star who once boasted that his band "was more popular than Jesus" -- but all John Lennon really wanted later in life was to stroll through Central Park and sing for his baby son, Sean.

That's according to Lennon's widow, Yoko Ono, who detailed for The Post the couple's amazingly simple lives in the days leading up to his murder -- 25 years ago on Thursday -- outside the Dakota apartment building on Central Park West.

"We did everything a normal couple would do -- in New York, we felt like we were two kids playing house," Ono recalled in a recent e-mail interview.

She said she and her husband loved that the city "was the most happening town at the time. Whatever we did, we enjoyed every moment of it."

But there were other, more important things to her famed husband than partying with big-shot celebs and being with his adoring fans, Yoko said.

Living quietly together as a family allowed Lennon to be a best friend, mentor -- and even music teacher -- to their beloved son, Sean, then 5, she recalled.

"John loved just being a family," Ono said.

At bedtime, "John's the one who read and sung to Sean. ... [And] Sean learned how to play the guitar from his dad."

Lennon continued to play his guitar and write songs, too, she said.

"Music and John were inseparable. There was always music in our life."