Sextortionists sent a grieving South Carolina lawmaker a sick message gloating about driving his teenage son to suicide — while threatening to release nude photos and demanding more money.

State Rep. Brandon Guffey, 54, told CNN that he got the Instagram message on the day his son Gavin would have turned 18 — and less than a month after he found him dead last year at their family home in Rock Hill.

“It said, ‘Did I tell you your son begged for his life,’ with a laughing face emoji,” Guffey told the outlet.

The sick, tragic crime was behind Guffey introducing “Gavin’s Law,” which was passed by state senators Thursday and is expected to be signed into law soon.

It threatens scammers who extort a minor or an at-risk adult with up to five years in prison for a first offense.

Guffey said he had no idea his son, a recent high school grad, was being blackmailed when he found him dead in the bathroom last July after hearing the loud thump of his body hitting the floor after he shot himself.

“My initial thought was, this is my fault — I left the gun out,” he said, adding he will never forget the pain of realizing his son died by suicide.

The sick plot emerged in part after the sextortionists started barraging Guffey and his family — including his younger son, Coen, 16 — with Instagram messages demanding more money.

They then realized that Gavin thought he was sharing nude photos with a young woman who first sent him pics — only to be told they’d be released to everyone he knew unless he paid blackmail.

Gavin had used Venmo to send the scammers all the money he had: $25.

“He was telling them he would get them more money, please don’t send these images out,” Guffey told CNN.

“They didn’t care.”

The grieving dad said the scammers used disappearing messages to make “kids feel safe” that their intimate pics would be scrubbed.

“What they don’t realize is, someone has another device recording that device,” he said.

“If you can extort 10 teenage boys that aren’t gonna say anything for $100 each, and do all that with one image that you got from a girl, it’s fairly simple.

“And teenage boys, whenever they see they’re getting that attention (from a girl), they’re not necessarily thinking.”

The FBI said that last year there were at least 7,000 reports of sextortion of minors, with at least 3,000 victims, mostly boys. More than a dozen are known to have died by suicide.

The true number may well be way higher because “the shame, fear, and confusion children feel when they are caught in this cycle often prevents them from asking for help or reporting the abuse,” the FBI says.

When Gavin died, his dad was in the middle of his successful run for state representative — and briefly considered quitting to focus on hunting for his son’s scammers.

“My wife said, ‘Absolutely not. You’re one of the few people that have a voice that can get out there and truly make a difference,’” he recalled.

He stayed in office, with “Gavin’s Law” his first order of business.

“I feel like he (Gavin) would want me trying to save additional kids from ever having to feel the way that he felt at that time,” he said proudly.

An FBI spokesperson told CNN that no arrests have been made in the Guffey case. The rep declined to provide additional information, citing an ongoing investigation.

If you are struggling with suicidal thoughts or are experiencing a mental health crisis and live in New York City, you can call 1-888-NYC-WELL for free and confidential crisis counseling. If you live outside the five boroughs, you can dial the 24/7 National Suicide Prevention hotline at 1-800-273-8255 or go to SuicidePreventionLifeline.org.