I’ve lied. I’ve cheated. I’ve destroyed relationship after relationship. All to avoid ever having to look at myself.

“But I’m so much fun!!!” I used to scream to anyone who dared criticize me or question my feckless actions as I wandered around Manhattan like a feral beast. “Everyone tells me I’m so much fun!”

Yes, I suppose “fun” is one word for it. “Sad” is another. Sad, and let’s be real: very, very bad.

I’ve had folks tell me before that as a dating columnist for the New York Post my life seemed like Carrie Bradshaw’s.

Sure, I suppose. If Carrie Bradshaw had a drinking problem. And a sex addiction problem. And, well, all the problems.

Growing up in San Diego, I had my first drink at 13. Two short years later, while blackout drunk, I lost my virginity to rape at the hands of a distant relative while spending the summer in Portland, Ore.

This was long before the #MeToo era. I blamed myself — and my parents blamed me, too. Addiction was a vicious cycle for me: Hate myself. Get wasted to forget. Hate myself for getting wasted. And the cycle repeats.

By its very nature, addiction is a battle you can never win. A little just makes you want it all. Two or three or twenty drinks stops being enough. A one-night stand stops being exciting.

In 2008, I gave up my dating column “About Last Night” in The Post in order to increase the chances of the upper-crust man I wrote about called “Super Preppy” asking me to marry him. But one night, after two years of dating, I just . . . snapped. I realized: He was never going to marry me. So after far too many martinis and a lot of desire for revenge, I simply decided to do the most “unwifeable” thing possible. I met two hot Italian pilots on the street, bummed a cigarette, and took them home for a night of sex, debauchery, and, well, the opposite of a marriage proposal.

Things spiraled out of control after that.

When I was at my most self-destructive, I was hooking up with drug dealers and answering ads on the Craigslist’s Casual Encounters section posted by strange men looking for “snow bunnies” (girls who did cocaine). All told, I fooled around in some form with a dozen men from the site. All told sexually, my number is not too far off from other New York women I’ve met — under 100, over 50 — but it wasn’t so much about quantity and more about total lack of quality.

One time, I posted online that I was looking for something akin to a sugar daddy. The first few guys that responded — before the ad was taken down because it probably sounded like blatant prostitution — all sounded like cops, and I chickened out. Another night I considered taking “100 roses” from a sad little man who posted that he was “looking for a girl to show off.” (One rose is code on Craigslist for one dollar.) I didn’t take the money he had laid out. Instead, we sat uncomfortably on the couch together watching “Apollo 13.” Before I got up to leave, I asked if he’d tell me his real name. He refused. What if someone found out?

A friend of mine, the notorious and often shocking comedian Jim Norton, once listened to me patiently as I described a night of doing coke and fooling around with an S&M couple before later meeting and sleeping with another stranger at 5 in the morning who had responded to my incredibly subtle posting on Craigslist entitled: “Need to get f–ked right now.”

Norton responded to my “wild and crazy” story with something I didn’t expect: concern.

“Jesus, Mandy,” he said. “You need to be more careful.”

As much of a wake-up call as that should have been, it was something far subtler that led me to realize I needed to stop living like my life was one long hilarious prelude to a suicide. After getting debased at a sex club party (okay, that part wasn’t subtle), I felt depressed and alienated that the guy who took me (just some random filmmaker who I met at a Page Six going-away party) seemingly blew me off. Desperate to recreate the high, I went home with a man who, after doing enough drugs with him, I came close to having sex with — before realizing I really had no desire at all.

“Let’s be friends,” I told him as I went to leave.

“I don’t think so,” he said.

This event mentally bottomed me out. None of this was fun anymore. It triggered the worst depression I’ve ever experienced.

On June 28, 2010, I swore off drugs and alcohol once and for all.

But, as anyone who’s ever experienced it in their own life knows, addiction is akin to one of those Whac-A-Mole games. Whack one thing down, another pops right up. Once substances were off the table as an option, I became even more addicted to sex.

To absolutely no one’s surprise, it all came crashing down when I ran out of money and ran out of men. Moving back home to live with my parents at the age of 36 with less than $300 in the bank, I knew it was time for me to finally look at myself — and every bad thing I’d ever done.

Self-care became a full-time job, and I went to 12-step meetings like my life depended on it. Because, with addiction, it often does.

I was determined to find out why I kept degrading myself and hurting so many people. After several years, I grew to accept and forgive and even integrate what darkness lurked beneath the surface — so that it didn’t consume me.

I decided to embody the old adage that there is no greater disinfectant than sunlight.

I figured out that having a checkered past doesn’t mean you need to destroy your life because of it. Gravitating toward the risqué, questioning the status quo and defying convention (at least when you do it in a healthy and honest way) are some of my favorite parts of myself.

I realized I really didn’t want to change myself in order to fix the many “deal breakers” men saw when they looked at me. I also doubted that I’d ever get married again.

My first marriage in 2000 at the age of 25 ended in a messy divorce in 2005 (weeks before starting at The Post). And a lot of my self-hatred (and subsequent addiction) came from trying to suppress myself for other people.

Maybe I was “unwifeable,” I joked to friends and family. Maybe I liked that about myself.

Eventually, that’s exactly what happened. Something revolutionary. I learned to like myself.

I stopped letting life happen to me. I stopped thinking chaos was glamorous. I stopped pretending. I returned to New York again (taking a job at xoJane in August 2012) and was able to survive.

Right before Valentine’s Day in 2015, I was hired for $20,000 by a dating website to go on a spree of romantic stunts (including walking around Times Square wearing a sign that I was single). During this time, I met a man at a comedy club who caught my eye. He looked like a private detective wearing a trim gray suit and a scowl. I asked him if he’d be up for participating in one of my “stunt dates.”

In a perfect twist of irony, it took something as “fake” as a stunt date to make me finally get real.

At the very start of our date, I handed him a piece of paper with a list detailing all of my “Relationship Expectations.” I spelled out what I wanted, really forcing myself to think about it: I didn’t want to be cheated on. I didn’t want to be insulted. I wanted to be treasured and loved.

Did that make me “unwifeable”? I didn’t care anymore.

I expected the date to last two minutes because he was being given a list of emotional demands right away — like, before we even ordered. Instead, he read it over carefully and quietly while I sat in the coffee shop sweating bullets.

“I don’t know,” he said, and then a smile broke through, “this all seems fairly reasonable.”

A stand-up comic (of course), my husband Pat Dixon proposed to me in under seven months. I got engaged on the last day of my thirties on the steps of Times Square.

This unlikely redemption tale is what led me to write the most difficult story of my life — my memoir, “Unwifeable” — as a tribute to anyone who feels trapped: in their past or the present, as the hero or the villain, as the wifeable or the unwifeable.

Honestly, I don’t think I would be as happy a wife if I hadn’t been so unwifeable.

And I don’t think I could have ever found my good without coming to terms with everything I’ve done that was so very, very bad.

“Unwifeable” (Gallery Books) is available now from retailers everywhere.