Howard Stern has a massive regret — one he says “brings him to tears.”

In a recent interview with Rolling Stone for the magazine’s cover story, the shock jock said he wishes he could apologize to the late actor and comedian Robin Williams for the way he treated the “Mrs. Doubtfire” star during an interview on his radio show, “The Howard Stern Show," in the 1990s. Williams died by suicide in 2014 at 63.

“In my mind, I knew all the answers. The audience won’t sit still for anything that’s more than 30 seconds long. All they want is to be shocked and outraged. That’s where I was at in my life,” he began. “I also have a regret about Robin Williams that haunts me. I was so angry at the world. I love Robin Williams, and yet if he came into my studio, I had to act like I didn’t love him. I’d be, 'F--k you.'"

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Stern, 65, then said he was more concerned with the attention remaining on himself rather than his guest — which, in this instance, was Williams. Stern said he took aim at Williams, specifically over a cheating scandal at the time.

"I love Robin Williams, and yet if he came into my studio, I had to act like I didn’t love him. I’d be, 'F**k you,'" Stern said, in part. (Getty/Reuters)

“I was a baby. I want every listener. I want everyone focused on me. You’re not going to be funnier than me. You’re not going to come into my studio and steal the moment from me. This is who I was. Rather than say to Robin Williams, ‘My God, you’re here,’ and celebrate an amazing talent and the beauty of that guy’s career, he walks in and I start in, ‘Hey, you’re f---ing your nanny,’” he said.

“Bam, sledgehammer. Sock him right in the f---ing head. A--hole. Me, not him. And my audience is cheering me on because who does that? There’s a lunatic loose from the mental asylum,” he added.

When asked what “made [him] change,” Stern had a candid response: psychotherapy.

“I’ve learned there was a way to talk about what was going on in Robin Williams’ personal life. I could’ve expressed to him the beauty of Robin Williams. Who knows what he would have revealed? Who knows what impressions he would have broken into? It brings me to tears to imagine what that moment could have been like,” he said.

“I’ve learned there was a way to talk about what was going on in Robin Williams’ personal life. I could’ve expressed to him the beauty of Robin Williams. Who knows what he would have revealed? Who knows what impressions he would have broken into? It brings me to tears to imagine what that moment could have been like."

— Howard Stern

“Some people in my audience would say, ‘Man, you don’t kiss anyone’s a--.’ It ain’t about kissing anyone’s a--. It’s about, 'Sh-t, I love this guy.' I want to tell him what he did for me when I was lonely and couldn’t find a friend. If I saw him in a movie or even ‘Mork & Mindy,’ he just brought some goddamn pleasure into my life, which is the whole reason I got into radio. I wanted to bring people pleasure.”

Stern then revealed he attempted to reach out to Williams at one point to apologize. But it was too late.

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“I had this idea that I gotta call him and apologize. I started to put it in process and see if he would take my call, but he killed himself,” he said. “I get chills when I tell you.”

Separately, Stern revealed this week on “The Late Show with Stephen Colbert” that President Trump was “one of the top five guests of all time” on his radio show.

“It was wild every time,” he said, in part.