The adult children of Gilgo Beach murder suspect Rex Heuermann are living in a “surreal, waking horror show,” according to an attorney who says they hired him to protect them now the investigation is “heating up.”

“They’re constantly… having to reevaluate what is happening to them, almost in real-time,” Vess Mitev told Fox News Digital of how Christopher Sheridan, 33, and Victoria Heuermann, 26, are coping with their dad’s bust last month.

 “[They’re] trying to regain some basic sense of normalcy, which is completely impossible at this point.

“They’re living in a surreal, waking horror show.”

Both Christopher and Victoria – who lived with Heuermann, 59, and wife and mother Asa Ellerup at their ramshackle Massapequa Park home – are “bystanders who are caught up in this developing legal case of the century,” Mitev said.

The siblings hired him because “their rights and liberties have to be protected,” he said.

“And that investigation… is now heating up with the DA handing over troves of documents last week, and… the leads the DA may be pursuing, whatever they may be, at some point may intertwine… with the rights and remedies that my clients have and enjoy under the Constitution and under the laws of New York,” he told Fox.

Mitev was not immediately available early Tuesday to elaborate on specific concerns.

Nearly one month after Heuermann’s bombshell arrest near his Manhattan architect office, Christopher and Victoria ask that their “privacy, which is completely eroded under the harsh glare of the spotlight” be “maintained and to whatever minimum degree it can be at this point,” the attorney added.

Christopher, who has special needs, was previously pictured looking distraught beside his mother on the front porch of their First Avenue home.

Ellerup and her children were only able to return to the ranch-style home after investigators practically gutted the structure and yard while combing for evidence during a nearly two-week search.

“Obviously, the deplorable conditions that their house was left in — torn apart from the floorboards to the shingles, basically — is their paramount concern,” Mitev said.

Ellerup previously told The Post that her children “cry themselves to sleep at night.”

Ellerup and the children were “blindsided” by the charges against Heuermann, which include multiple counts of first- and second-degree murder.

Ellerup, who is originally from Iceland, filed for divorce less than one week after her husband of over two decades was arrested.

A GoFundMe campaign for Ellerup that was started by Melissa Moore, the daughter of the Happy Face Killer, recently raised its goal to $50,000 after quickly surpassing its original $25,000 threshold.

Heuermann was arrested on July 13 and charged with the infamous killings of Melissa Barthelemy, 24, Megan Waterman, 22, and Amber Lynn Costello, 27.

All three women’s bodies were found strangled and wrapped in burlaps off Ocean Parkway near Gilgo Beach in December 2010.

Heuermann is also the prime suspect in the death of Maureen Brainard-Barnes, 25, who was the first of the so-called “Gilgo Four” to go missing.

At a brief court appearance last week, the architect looked on impassively while prosecutors vowed to hand over eight terabytes of evidence by September 27.

The massive collection includes 2,500 pages of crime scene photos, autopsy reports, and over 100 hours of surveillance footage, Suffolk County Assistant District Attorney Santino Martino told the court.

Heuermann pleaded not guilty to all charges one day after his arrest. As of Tuesday morning, police have not linked him to the seven additional bodies that were also discovered near Gilgo Beach between 2010 and 2011.