Before Kenny Anderson can start his car, he blows into a breathalyzer, as one of his children sits beside him patiently.

The New York City legend lectures another son about the importance of safe sex, and the teenager quickly reminds his father he isn’t the one who has eight kids with five different women.

The former NBA All-Star makes a call to discuss his investments, more important than he ever expected them to be after earning $63 million in his career, before filing for bankruptcy in 2005.

Anderson can’t hide his mistakes any more than he could conceal the extraordinary skills that made stardom seem certain before he hit puberty.

In the documentary “Mr. Chibbs” — a nickname given to him by his mother — that opens at the IFC Center in Greenwich Village on May 3, Anderson is followed through a candid, sad and hopeful journey, in which he struggles with his post-NBA identity, fading fame and the consequences he never considered.

The “walking mistake” treats the scars — being sexually abused as a child, the 2013 DUI which cost him his job as a high school basketball coach, his multiple infidelities — like souvenirs, collected and showcased to remind him who he never wants to be again.

“If you’re gonna tell the world that this is what you’re about now, and then they see me next week at a strip club with bottles, and walking sideways out of there, people are gonna laugh that you’re living fake, and that’s not me,” Anderson told The Post this week. “This is good pressure to better yourself. I can’t be going back and doing some nonsense.

“It’s emotional, and I don’t want to keep going back, but to go forward, I had to tell where I came from. Thank god I didn’t go down a real dark path, and go to jail or lose my life. All the things that I went though, I’m able to learn from and move on.”

Anderson often looks back because so many conversations take him to the time where he is allergic to fat, and salt hasn’t yet infiltrated his beard; where he still breaks ankles, and his knees don’t ache.

Sometimes, Anderson turns the clock, sending strangers on google searches to confirm his celebrity. More times, Anderson is along for the ride.

When he returned to his old neighborhood in Queens — LeFrak City — on Tuesday, old security guards embrace the former resident, who turned neighbors into fans, and terraces into bleachers.

The court bearing his name has been torn up, but he can spot the corner where his family’s furniture was placed after being evicted. Raised by a single mother, Joan, Anderson shared a close, yet complicated relationship with the woman he adored — a woman he watched abuse drugs and alcohol, and die shortly after he retired in 2005.

When Anderson returns to Archbishop Molloy High School, the lobby is remodeled, but the hardwood where he became New York’s first four-time All-City player is untouched. Kids — one calling him “Mr. Anderson” — ask for his picture. Adults do, too.

“It’s never been the same without you,” Mrs. Lonergan, Anderson’s biology teacher, tells him.

Anderson walks past his many awards proudly hanging in the trophy case, but he is more excited talking to Ms. Longerano about the 83 he got on the math regents — “that was like 100 to me” — and still laughs about the year he played flute in music class. The 46-year-old invites several faculty members to come to his film this week. They will try, but they are busy this time of year, each relays.

Other students need them now.

Anderson needed help then, but he let no one know. He was famous and talented and trying to forget being sexually abused by two different men as a kid.

“Some of those demons from getting abused, I started taking advantage of the fame I had,” said Anderson, who currently sees a therapist once a week. “I was Kenny Anderson. People would let me do what I wanted to do and it would be all right. As far as the womanizing, when you get molested, you’re trying to protect your ego and you’re trying to hide [and you say], ‘I got all the girls. I got all the women.’ I didn’t realize any of it. You gotta get therapy. You gotta get professional help.

“I go through moments of depression. I fight that. It could be Saturday morning and I wake up, and the wires don’t feel right. I lock myself in a room because I don’t want my family [upset]. It’s a challenge.”

Anderson is trying to be a better husband, 10 years into his third marriage, to Natasha. In the film, she discusses her struggles trusting him.

“I think all men have a desire to be with multiple women,” Anderson said. “How do we sit back and control our lust? That’s where the control, coming at 46 years old, I’m much better at that than at 23 or even 30. You have to shut it off, understanding what’s at stake for you to lose for doing what you’re thinking of doing.”

Anderson is trying to be a better father — better than the guy Kenny Jr. said he doesn’t “need,” and learned about by researching for projects.

“I fight with them every day, and they argue with me and get mad at me and don’t call me, and it’s tough, but I made those kids and I have to take care of them and I have to take the beatings,” said Anderson, whose first child was born while he was at Georgia Tech. “I just took care of my kids financially. I wasn’t in their lives. That bothers me, but I can’t go back. I lost that time. I gotta figure out how to make it right and let them know I’m here.”

The former point guard constantly contrasts his difficulties in life against the ease of playing basketball. Anderson led Georgia Tech to the 1990 Final Four, was picked second overall by the Nets in the 1991 NBA draft and was an All-Star by his third season.

He has no regrets about his “solid” 14-year pro career, even if he was partying as often as he was practicing. It’s the rare “what if?” that doesn’t affect him now.

“I was drinking, hanging out, [goofing] around. If I would’ve worked a little harder and curbed some of the things I was doing off the court, I would’ve been great,” Anderson said. “It was easy for me. My talent was enough for a certain period of time, then talent fades and I didn’t work as hard as I could have.

“And some things are out of your control. Drazen Petrovic dies [in 1993]. Who knows what happens if me and Derrick [Coleman] and Drazen play another two years? I don’t know. Maybe everything would’ve looked different, but I don’t care. I had a great run. I tell my son: If you have half the career I had, you did great.”

Anderson lived a life of luxury, owning up to 11 cars at one point, and spent like he had a lifetime contract. There were also eight children to support, and his mother, and countless friends who looked at him like an ATM.

He still “lives comfortably” and “everything is taken care of” in what he describes as a “high, middle class” setting in Pembroke Pines, Fla., surrounded by far more than he hoped to have growing up.

“Did I lose a lot? No. I spent it. I didn’t get robbed. These were decisions that I made,” Anderson said. “Your family can be your worst enemy. Rest in peace, my mother, she spent a lot of my money, but that’s your mother. I might’ve done it a little different, but I would’ve spoiled her right now again. She wanted to live a carefree life, and I was able to do that for 20 years. The kids are a blessing, but it was very expensive.

“I got some great advice. I just didn’t listen. I was like, ‘This is my money. I know what I’m doing.’ I could’ve listened, but I didn’t, so who am I going to blame? I blame myself. It’s gone. Now figure out your life.”

Life after basketball mostly has been spent running alongside it. He coached in the CBA, and in the trampoline-infused SlamBall, before making an “ignorant” appearance playing in front of Kim Jong-un in North Korea.

He currently coaches his son, Kenneth, on an AAU travel team, and shuttles him and his stepdaughter, Tiana, back and forth to school.

Anderson also runs a basketball clinic in Tampa, and wants to become a life coach and start a mentorship program.

In the film, he often fights back tears, speaking to various groups of students, highlighting every mistake he made, in hopes they can avoid them.

“They see what he did right, what he did wrong, and that’s why it’s fascinating to see where he is now,” said director Jill Campbell, who worked alongside executive producer Barry Greenstein. “He was in a mid-life crisis. It’s a universal story. We’re all struggling in life, even if you’re a basketball prodigy.”

Everything is on the screen. What’s next is harder to see.

“I’m trying to figure it all out, what I’m gonna do to reinvent myself,” Anderson said. “It’s in my mind every day. I’m a work in progress. I want do something I love and have passion for. I’m just trying to give hope. I want to give back.

“Maybe I can catch some kids along the way, fighting their own demons, and help turn a kid’s life around. I think that’s my calling. I think I can do that and I’ll love it, but sometimes life ain’t fair. You want to do certain things, and life ain’t gonna set you up that way. I hope my calling comes.”