Regrets, Perez Hilton has a few.

Mario Armando Lavandeira, Jr., created one of the most notorious gossip pages by being one of the cattiest voices online, mocking celebrities and scrawling nasty comments on pictures. It made his Perez Hilton site, founded in 2004, extraordinarily popular, but he didn’t quite realize the antipathy he’d built up.

In 2010, Rutgers University student Tyler Clementi committed suicide by jumping off the George Washington Bridge. His roommate had used a webcam to spy on Clementi, saw him kissing a man, and invited others to watch. Writer Dan Savage started a campaign in response, It Gets Better, and Perez offered his support. Since Perez had used his site to out celebrities without their consent, the backlash was immediate.

“People wrote such hateful comments that I couldn’t bring myself to read even half of them,” Perez, now 42, writes in his new memoir, “TMI: My Life in Scandal,” (Chicago Review Press), co-written with Leif Eriksson and Martin Svensson.

“The strength of the hate storm really shook me, and popped the bubble I had been living in. I realized for the first time that it wasn’t just a handful of people who disliked what I did — it was the overwhelming majority. I finally understood that the things I wrote genuinely hurt people, and deeply.”

So consider “TMI” a mea culpa, with stories that often revolve around how Hilton moved in the corridors of celebrity, then weaponized his site against those he felt wronged him

Hilton reveals that in 2011 he met with Ariana Grande and her mother about managing or at least consulting on her career. When they turned him down. “I was really hurt, so for years afterward I was super petty toward Ariana on my website and on social media. I regret that.”

Some celebrities hated him. Roseanne Barr said something about “wanting to kidnap me and take me to her farm in Hawaii so she could say I was trespassing and then shoot me.”

“I didn’t care,” Hilton writes. “That was partly down to being young and believing I would be successful forever, but it was also because I thought I was happy. In reality, I was drowning in negativity. I was stuck playing a part, too afraid to change, too afraid of losing my readers if I suddenly stopped being so mean.”

He began to understand the depth of the damage after will.i.am’s manager knocked him unconscious at a Toronto awards show party in 2010.

After getting called out for his meanness first by Fergie, then by will, will said to him, “Why’d you disrespect me, man?”

Hilton answered, “I don’t have to respect you. You’re such a f–. Stop being such a f——t.”

The next thing he saw before falling unconscious was will’s manager’s fist coming toward him.

He had no bigger love-hate relationship than with Lady Gaga, whom he met in 2008.

“I’ll never forget the way she seemed to be glowing,” he writes. “There are certain people you feel like you’ve known for a long time from the moment you meet them, and that’s exactly how it was with Gaga.”

Soon, the two were talking on the phone for hours each day. Hilton writes that they hung out so often they started spending holidays together, and he called her “wifey.”

But fame, Hilton writes, changed her.

“As she became Lady Gaga to the world, she began drinking in a different, more serious way, while also popping all kinds of pills.”

Instead of confronting her, Hilton defended her at every turn, even when it was unwarranted.

When he and Gaga thought Christina Aguilera copied Gaga on her “Bionic” album, Hilton started trashing Aguilera mercilessly in his column, even though the singer had just performed at his birthday party a few months earlier.

“I started giving Christina all kinds of terrible nicknames,” he writes.

“Looking back now, it’s one of the things I’m most ashamed of, and I can also see that Gaga was using me as a tool — not only against Christina but against other rivals too. She never explicitly asked me to write nasty things about people, but by moaning to me she made me feel like I, her best friend, should do something about it.”

His friendship with Gaga imploded in 2011, shortly after the release of her “Born This Way” album.

Hilton flew to Australia, where Gaga was doing promo for the album, to interview her for a TV special. After the flight, instead of pushing the interviews to the following day, they sat for them that night, with both of them jet-lagged and Gaga also drunk.

When Hilton asked about her song “Judas,” which had attracted some controversy due to religious imagery in the song’s video, Gaga exploded.

“Her eyes turned dark and she snapped at me, ‘What are you doing? Are you trying to make me look bad?’”

Hilton was taken aback, and changed the subject quickly. But asking about her boyfriend instead did little to placate the superstar, who glared at him and said, “I’m ending this.”

“By this point, Gaga seemed convinced I was trying to catch her out,” Hilton writes.

“If she hadn’t been so drunk and if she had just thought it through, she would have seen that that was the last thing I wanted,” Hilton writes.

Gaga stormed off to her hotel as Hilton ran after her in tears. She finished the interview a few days later, but something had changed. Their friendship was over.

Two years later, Hilton was apartment hunting in New York when his email account suddenly began filling up with hate mail, with people accusing him of tormenting Lady Gaga.

“After reading a few of the messages, I realized that Gaga had tweeted something about me earlier that day, so I checked what she had written,” he writes.

“She accused me of following her, of being a creepy stalker. My head was spinning. Had she gone completely crazy? Was she so drunk or high on drugs that she had finally lost all sense of reality?”

As he kept reading, he realized that he had unknowingly looked at an apartment in Gaga’s building. A fan of hers saw him and tweeted the news to Gaga, which set off her tirade.

“Why, after two years silence, would I suddenly start stalking her?” he writes. “It was sheer persecution mania, and once I got over the initial shock and deleted all the hate mail, I actually just felt sad for her.”

Of course, Perez Hilton being Perez Hilton, his regrets don’t stop him from spilling even more gossip.

He relates how he met the inspiration for his nom-de-plum at New York Fashion Week in 2005, describing Paris Hilton as “one of the biggest stoners I ever met.”

“She used to smoke weed every day, from first thing in the morning till late in the evening — a wake-and-baker, as they call ’em.”

And he tells the truly bizarre story of New Year’s Day 2007, in a nightclub at 2 a.m., when John Mayer plopped down between him and Mayer’s girlfriend, Jessica Simpson.

“I’d never met John before, but the minute Jessica introduced us, he began chatting to me. It was almost like he had been waiting to meet me,” Hilton writes. “Suddenly, he leaned in to me and said, ‘I like to watch gay porn, you know.’ ”

Hilton was stunned into silence as Mayer talked about his favorite gay porn star and how the man “really turns me on.”
“Everything happened very quickly after that,” Hilton writes. “John leaned in close and pushed his tongue into my mouth, and before I knew what was happening, he was full on making out with me.”

As this happened, Hilton writes, Simpson stared at them, “frozen,” before deciding to join in.
“She blushed when our eyes met, and quickly covered her face with her brunette hair,” Hilton writes. “. . . John groaned quietly as he kissed me, but I was just trying to work out what was going on.”

In a later interview with Playboy, Mayer said it was an act, saying that he thought Hilton was “acting as though he had just invented homosexuality. All of a sudden I thought, I can outgay this guy right now.” Hilton called him “self-hating.”

Hilton, now a father of three, still runs his gossip site, but says he’s trying to make it kinder and gentler.

“One of the many things I regret is that I hurt so many people by giving them nasty nicknames, and above all that I was unkind to the children of celebrities,” he writes.

“I now see that I never needed to be so mean or cruel. I would’ve been fine anyway, just by being who I was.”