Transgender killer Robert Dorgan murdered his 23-year-old son and ex-wife and critically wounded her parents at Monday’s horrifying massacre at a Rhode Island high school hockey game, it was revealed Tuesday.

Tragic Aidan Dorgan had just graduated from college as an engineer — designing a robot to hand out Halloween candy as part of his studies — and gotten engaged last year, the Providence Journal said.

Aidan’s mom Rhonda, Dorgan’s 52-year-old ex who was slain alongside her son, was meanwhile a “beacon of light” and the “sweetest, loving person this earth,” a pal wrote on Facebook.

“Our family has been forever changed by the tragic events at Lynch Arena, where we lost our beloved brother Aidan and their mother Rhonda, who was also my stepmother,” Amanda Wallace-Hubbard said on a GoFundMe page.

“In addition to this unimaginable loss, their grandparents are currently in critical condition, fighting for their lives,” she said.

Robert and Rhonda’s teenage son Colin — a star multi-sport athlete — was competing on the ice just feet away when the dad launched his heinous rampage, killing the boy’s mom and older brother.

Robert, 56, and Rhonda also had a daughter, Ava — who told the Boston Globe that Colin is doing “OK.”

Ava, a nursing student, said her father worked on boats and had no history of violence. She said she wasn’t aware he owned guns.

When the outlet asked if she and her siblings were close with their father, she said, “We were not in the last few years.”

A relative has said Dorgan had a total of six children, including three with Rhonda.

Aidan had been captain of his high-school hockey and lacrosse teams, as well as a National Honor Society member, the Journal said.

He “was a bright student who made both the President’s and Dean’s lists during his time at Merrimack,” Merrimack College President Christopher Hopey added in a statement, according to the Providence outlet.

“He was very involved in the School of Engineering and Computational Sciences and embodied a true pursuit of knowledge,” Hopey said. “At the 2025 Research & Creative Achievement Conference, he was part of a group that presented on robots the group had built to address specific challenges.”

After graduating from college, Aidan had been interning at General Dynamics Electric Boat in Groton, Conn., according to his LinkedIn page.

“After years of education and applications, I’m thrilled to finally start living out my dream of working in the shipbuilding industry,” he wrote.

Wallace-Hubbard added in the family fundraiser, “Ava, who is working hard as a nursing student, and Colin, a 17-year-old senior in high school, are now facing the future without their parents and older brother.

“The weight of this loss is something no one should ever have to bear, especially at such young ages.”

Wallace-Hubbard said Ava and Colin are determined to continue their education and “build a life that honors the memory of our loved ones” despite a tough road ahead “filled with uncertainty and financial challenges.”

So far the fundraiser has collected at least $57,000 of its $65,000 goal.

After his sadistic rampage at the Pawtucket ice rink, Dorgan, who went by Roberta Esposito and underwent gender reassignment surgery in 2020, took his own life.

One of his daughters told local NBC affiliate WJAR that her father has struggled with mental health issues for his entire adult life and that “I think his gender-identity issues are a symptom of a deeper issue.”

Court records show two of Dorgan’s former wives filed child-support cases against him just five months apart in 2016.

Former wife Heidi Wallace, 62, who filed in January of that year, declined to speak when reached by the Globe on Tuesday.

“My family is very, very … We can’t talk about this right now,” she told the outlet while sobbing.

The other child support case was filed in May 2016 by Marlyse Dunbar, 57.

The Post left voicemails for both women Tuesday afternoon but didn’t hear back.