Ryan O’Neal. You read he has cancer. Now read his autobio “Both of Us: My Life With Farrah.” Crown publishes it May 1. Why now write about Farrah Fawcett?

“I don’t need money, I’m 71. Not looking to jump-start a new career. I did it for her. I wanted everyone to know her. It took me six months. I stopped, I started. Also it was a writer’s good pitch. He said, ‘You made “Love Story,” so we make this a love story.’

“She and I were together on and off 18 years, and I always kept journals. Lots of information. Every night I wrote in a diary.

“Ours was a wonderful but imperfect love. I’m a semi-nice guy, but I was jealous, insecure, everything you don’t want in a man. Most times I don’t like me. It’s all I talk about now.

“Look, I don’t give myself a break. I had four children. Only sportscaster Patrick’s OK. Griffin’s in prison. Redmond, who feels terrible guilt, is in rehab. Tatum, rehab. I had my own problems. Is all this my fault? I guess, yes. When his mother was dying I paid sheriffs $800 overtime to bring Redmond in chains. I keep all her mementoes in a safe to give him someday.”

How did Ryan meet Farrah?

“In Canada her husband Lee Majors took me to play racquetball. They were together 11 years. Didn’t take long to see they were over and it’s time for ‘Next’!

“So, now, with a second chance at life, my leukemia’s in check 11 years, comes this new diagnosis. The urologist biopsied one section and said it’s Stage 2. I said, ‘No, no, you mean I’m working on Stage 2?’ I can’t say I’m comfortable with this. It’s not a nice place to be.

“But some genius South Korean doctor freezes that part of you, so there’s no surgery or radiation. May 10, after I’ve promoted the book, I’m having that done . . . I also just got new titanium knees, so which part of me would you like to have dinner with?”

Tatum’s reaction to the book?

“I sent it. She waited a week then texted her OK. A driving force in it, she doesn’t come off well. When she won an Oscar in our ‘Paper Moon,’ she was 10. Beguiling. We bonded. Then came Farrah. Our love occasionally wobbled but it held. That’s when Tantrum, as I’ve called her, disappeared for me. Changed her phone number. I was the problem.

“Tatum’s complicated. I think she’ll come out of rehab fine but, then, I thought that before.”

ABOUT a politician’s speech: “He talks like a toreador. A point here, a point there and bull in between.”

VANITY Fair and Graydon Carter’s Film Festival party was atop the 60 Centre St. courthouse steps. Soon they’ll need younger guests or stretcher-bearers. Mutineers walking the plank don’t climb that many stairs.

Supreme Court Captain Michael Castellano showed Judge Judy this 1927 courthouse features Mayor Jimmy Walker’s girlfriend Betty Compton. She’s inside, on the ceiling, a bare-breasted fresco under the entrance rotunda.

Michael Douglas with stunning Catherine Zeta-Jones explained his dad’s writing “I, Spartacus,” an autobio. Michael said, “Maybe I’ll play the son in the movie.” Kirk Douglas said, “Forget it. I got George Clooney.”

Between everyone hugging Greg and father Ray Kelly, Billy Crystal told me “hosting the Oscars was fun. The aftermath stinks.” . . . LeeLee Sobieski shlepped around a white floor-length evening gown while Judd Apatow dressed like a schlub . . . Two non teddy bears Robert De Niro and Harvey Keitel went huggy. “He’s my friend,” explained Keitel.

About opening “Titanic 3D” in China, will James Cameron’s guest Wendi Murdoch ride his submersible? “No. It’s scary. Strange creatures in that seabed.”. . . Salman Rushdie, who hasn’t missed a party since Genghis Khan’s bar mitzvah: “My second novel ‘Midnight’s Children’ is becoming a movie.”

I left early. Takes time to rappel down those stairs.

ANYONE know most men want to breakfast with Britney Spears and most females want to share morning-after toast with Brad Pitt? . . . Then, if still hungry, they should do dinner at Italian ristorante Valbella in our Meatpacking District or Midtown on East 53rd or in Connecticut. Might see Joe Torre or R. Philbin there.

LAST week’s Rock and Roll Hall of Fame inductee has Rich Podolsky’s new bio, “Don Kirshner: The Man With the Golden Ear.” If your tin ear won’t grab the name, he’s the one who started Bobby Darin, Tony Orlando, Neil Sedaka . . . Listen, all together now, how about one day without a Beyoncé photo with the baby, with the hubby, in the pool, at the ballgame???

A BROADWAY bus has the recorded announcement: “Assaulting a bus driver is a felony.” The other morning came a glitch, and the recording said: “A bus driver is a felony.”

Only in New York, kids, only in New York.