It was the first Monday of April — fittingly the day after April Fool’s — and David Feherty was on a stage at a small theater in North Jersey doing what he does best: making people laugh and masking the pain from the laundry list of inner turmoil he lives with on a daily basis.

Growing up in Northern Ireland, Feherty was acutely familiar with “the troubles’’ in his part of the world. He never knew, though, that his own troubles, which have nothing to do with political unrest, would follow him for the rest of his life.

Before his two-hour set was to begin at the Bergen Performing Arts Center, the 60-year-old Feherty — with his Golf Channel interview show and his colorful analysis on NBC’s PGA Tour coverage making him one of the most popular figures in golf — sat down with The Post and spoke openly about the litany of personal challenges he’s faced (and still faces).

This is a particularly special time for Feherty, because he’ll be a part of the NBC broadcast team calling the British Open this week at Royal Portrush, which is just miles from the small town of Bangor where Feherty grew up.

This Open Championship is the first being played in Northern Ireland in 68 years, and Feherty said he’s been waiting all his life to work a tournament in his homeland.

Feherty is a fascinating man of life and career accomplishments who, in conversation, matter-of-factly transitions from his sharp wit to the sharp pain he’s endured and the struggles he still fights.

In one moment, he’s making you laugh with his self-deprecating humor.

“I went through a long stretch of getting hit in the nuts,’’ Feherty said while talking about his Golf Channel interview show, which has spanned sit-downs with not only golf’s best and most interesting personalities, but U.S. presidents and mega-stars from other sports. “[Tony] Romo hit me in the nuts with a football. Rory [McIlroy] hit me with a golf ball. Sergio [Garcia] hit me with a tennis ball. My testicles were a huge target for a while … and they’re not a huge target.’’

In the next moment, Feherty is opening up about his addictions to alcohol and drugs, being diagnosed with clinical depression and bipolar disorder and the death of his son, Shey, who took his own life on his 29th birthday on July 29, 2017, with a drug overdose.

“There’s no such thing as recovery,’’ Feherty said. “It doesn’t exist. It’s just, ‘You’re not f–king drunk.’ You’re either drunk or you’re not drunk. There’s nothing in between. So, right now, I’m not drunk and tomorrow it’ll hopefully be the same.

“Let’s put it this way: I’m glad they don’t drug test announcers. I would fail on several counts — amphetamines, mood stabilizers, the serotonin re-uptake inhibitors. I take 12 pills a day, which I hate. I hate having to take medicine, but I’ve tried it without and, man, it’s a lot worse.’’

All of this heavy talk seemed out of place with Feherty just minutes away from taking the stage to deliver comedy to 1,200 fans.

But it wasn’t. Nothing is out of bounds for the painfully transparent Feherty, who calls his comedy show “a self-defense.’’

Indeed, Feherty’s show is a diversion for him. It’s a two-hour escape from the demons that dog his soul every hour of every day — and the hysterical response from the audience is his elixir, replacing the vodka and Vicodin.

“There’s a knife edge there between comedy and tragedy,’’ Feherty said. “The comedy is a way to cope. I think most comedians are coping with something. Mental illness is one of the common denominators that comics have, whether it’s bipolar or depression. Lenny Bruce was schizophrenic. There’s a benefit to it. Painters and artists and musicians quite often are mentally ill in some way. So I don’t feel bad about it. I don’t suffer from depression; I live with it. And this helps me.’’

Asked what’s more terrifying to him, walking on that stage or standing over an 8-foot putt with a tournament on the line, Feherty doesn’t hesitate.

“Getting up on stage is the most frightening, because that could be the night that you suck,’’ he said. “You never know. That’s the same attitude I brought to the golf course and why I probably didn’t do as well as I should have on the golf course. If I was leading a tournament, I always, in the back of my mind, thought, ‘This is how I could lose.’ ’’

On this night, as with every night he stands alone on stage for two hours, Feherty does not suck. He’s witty. He’s warm. And he’s the truth. For all of these things, he’s embraced, as much for his humor as for his vulnerability.

There are a few people whom Feherty credits with saving his life.

At the top of that list is Anita, his wife of 23 years after his first marriage dissolved.

A close second is Tom Watson.

“Tom Watson and my wife have been the constants for me, always there whenever I’ve fallen,’’ Feherty said.

It was Watson who, in a way, scared Feherty straight in 2006, when he was working a broadcast for Canadian television in Prince Edward Island.

“I was doing the walking announcing for Nicklaus versus Watson and interviewing them both for the show the night before the round they were going to play,’’ Feherty said. “Tom put his hand in front of the camera and said, ‘You’re not well, are you?’ I said, ‘No. I’m not.’ I was in the depths of depression, drinking a bottle and a half, two bottles of whiskey every day and taking 20 or 30 Vicodins. I was in bad shape.

“Tom said, ‘You need to come with me.’ I said, ‘To where?’ He said, ‘To Kansas.’ I’m backpedaling a bit and I hear this voice behind me [Feherty using a spot-on high-pitched Nicklaus impersonation] say, ‘You need to go with him. You look like sh-t.’

“I’m being heckled by Jack Nicklaus and he owns a G-5 [jet], so Jack just flew us there to Kansas. It was Jack Nicklaus and Tom Watson who saved my life to a certain extent.’’

Far worse than Feherty’s depression and addictions was the loss of Shey, something he said will haunt him for the rest of his life. Shey’s death, Feherty acknowledged, knocked him off the wagon for a spell before he righted himself.

“He was lost in so many ways, [he] reminded me a lot of me,’’ Feherty said.

Despite such profound loss and his daily battle with his well-documented obstacles, Feherty powers on with his multi-tasking.

People forget that he was an accomplished professional player for some 20 years, winning five times on the European Tour, 10 times world-wide and playing on the 1991 Ryder Cup team.

Despite that relative success, Feherty is typically self-deprecating about his playing career.

“You don’t play golf for 20 years and make a living and not be competent at it, but I was never going to be one of those top-echelon players that won majors,’’ Feherty said. “I just didn’t have the work ethic. I was too lazy. The other thing is I didn’t want the responsibility. I didn’t realize this until I looked back on my [playing] career that I didn’t want the responsibility that came with being a major champion or a top-echelon player.

“You have to be in a place where you know you’re going to be uncomfortable to be that good, and I didn’t feel like I wanted to be in that place until I got into television. It was then when I felt like I’d come home almost. When I got into television, I didn’t really know that’s where I should be. But it’s probably where I should have been all along.’’

Feherty has turned his broadcasting career into a cottage industry. His interview show has become increasingly popular, with so many interesting subjects and his unique interviewing style setting it apart.

“The Tom Watson show, for obvious reasons, was special to me,’’ Feherty said. “Bill Russell was an amazing man. I’ve only had the feeling a couple times: When I shook hands with him, there was a warmth, an electricity almost. He had an aura around him that was comforting. Only thing I can compare it to was Arnold Palmer. He was probably the greatest winner in American sports, 11 titles. I interviewed President Clinton, President [George W.] Bush, President Trump twice.’’

The comedy show idea was conceived by Canadian promoter Brad Jones, who booked Feherty to come speak to some people at a corporate event in Jones’ hometown of London, Ontario.

After the event, Jones asked Feherty if he’d be interested in taking his show on the road.

“What blew me away was that nobody had ever approached him with the idea before,” Jones said.

Jones put together a proposal and the Feherty Off-Tour act was unveiled in November 2014.

“We’ve done about 120 shows, we go to a city and do three nights of shows,’’ Jones said.

Feherty said doing comedy “never crossed my mind.’’

“Our first show was in Calgary in 2014,’’ he recalled. “It was sold-out, 1,600 people. I remember how cold it was in Calgary. It was like 28-below. I lost a nipple in the parking lot.’’

Jones recalled Feherty doing three hours that first night “and people were peeing their pants.’’

“I said, ‘Hey, we want to come back here again, quit sharing all your stories,’ ’’ Jones recalled.

“There are people that have actually driven from far away to see the show again and I say, ‘Look, it’s the same sh-t,’ ’’ Feherty said. “They say, ‘We don’t care.’ ’’

When it was suggested to Feherty that he’s an extraordinary multi-tasker — with the live broadcast work, the interview show and the comedy tour — he joked, “I used to be kind of a uni-tasker. I was very poor at school, couldn’t pass an exam. I had attention deficit inside of me. Back then they called it ‘stupid.’ They’ve got a pill [Adderall] for ‘stupid’ now.’’

What does he get from comedy shows?

“There’s tremendous satisfaction in being able to hold an audience for over two hours, and to make them laugh,’’ he said. “I get a rush before I go on stage. Some nights are better than others, but they’ve all left me where I feel like I’ve come away with something. They know me a little better.’’

Asked what he would pick as his greatest accomplishment, the thing he’s most proud of, he said, “I have a little resentment from the way I was treated in school. I dropped out of 10th grade — and I was devastated by the fact that I couldn’t learn the way other kids did. I knew I wasn’t stupid, but I was made to feel stupid. So just having made a life out of that … ’’

Despite the lifetime of heartache and hurdles, it would be difficult for any of those people who once made fun of Feherty to argue that he’s hasn’t gotten the last laugh.