The Pennsylvania mom accused of killing her husband and their 3-year-old son at a Poconos resort showed no signs of trouble in a video call just hours before the attempted murder-suicide, according to her stepmom — who now believes she had planned it for weeks.

Metallica Rose Harrison, 27, had never shown signs of mental illness and appeared normal in a video call Sunday, soon before she allegedly stabbed her husband and son and tried to slit her own wrists and neck, her stepmom April Thetga told The Post.

“She had called and we’re video chatting, and then she says she loved us very much, just like she normally would,” Thetga recalled.

Metallica Rose Harrison, 27, who allegedly stabbed her husband Charles Harrison and their three-year-old son at the Great Wolf Lodge in Poconos. Chaz Harrison / FacebookMetallica Rose Harrison with her son in an undated photo. Metallicarose Harrison / FacebookCharles Harrison poses with his three-year-old son. Chaz Harrison / Facebook

“It wasn’t an odd conversation,” she said. “She didn’t give us any indication that anything was ever going to happen.

“It was a loving family. We’re just as shocked as everybody else.”

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Here’s the latest on the Great Wolf Lodge stabbing:

• Accused killer mom’s gas was set to be shut off over $30 unpaid bill after draining husband’s 401(k) to pay for Great Wolf Lodge trip
• Accused Poconos killer mom Metallica Harrison ‘never wanted to get pregnant’ — and hated son stealing hubby’s attention: warrant
• Metallica Rose Harrison’s tearful mugshot revealed as cops raid home after she allegedly butchered husband, son
• Stepmom reveals Metallica Rose’s chilling final call with family hours before she stabbed son, husband — and sign she planned killings for weeks

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Harrison’s family found it “odd” that the mom and her husband, Chris, were having an extended stay at the Great Wolf Lodge, but assumed it was because their “amazing” and “very happy” son Tristan loved playing in water parks so much.

They sent regular photos from their stay to show loved ones how much fun they were having.

Metallica Rose Harrison with her husband, Charles and her son in an undated photo. Chaz Harrison / Facebook

But after the murders, they were shocked to find out that the murder weapon was from a set of knives Metallica had brought from home, the stepmom revealed.

“I was told the knives came from her home. Her house. So to me, it was planned,” Thetga told The Post.

A butcher knife was found on the bathroom floor and a smaller knife in the bathroom sink, according to the police, who say Metallica called 911 to ask for help on how to kill herself after reporting the slayings.

As for the motive, Thetga said she and the rest of the family “don’t have one.”

A general view shows the Great Wolf Lodge in Scotrun, Pennsylvania, Monday. Mom Metallica Rose allegedly killed her son and husband at the lodge. Christopher Sadowski for NY PostMetallica Rose Harrison with her son and husband, Charles. Metallica Rose allegedly murdered her son and husband at the Great Wolf Lodge in the Poconos. Metallicarose Harrison / FacebookMetallica Rose Harrison with her son and husband Charles. Metallica is accused of murdering her son and husband while vacationing a the Great Wolf Lodge. Chaz Harrison / Facebook

“That’s the thing. I don’t have one. We’re just as shocked as everybody else. … We want answers,” the stepmom said.

“They were always happy. This is devastating.”

Harrison worked as an in-home caregiver and her husband was a cabinetmaker; they had leveraged his retirement account for home improvements and other expenses, in addition to funding the resort vacation, Thetga said.

Metallica Rose Harrison, center, poses with her stepmother, April Thetga, left. Facebook/April Thetga

She didn’t know whether the couple had borrowed against the account or withdrawn the money outright, but found the choice “odd.”