It’s every mother’s worst nightmare.

Pat Taccetta didn’t learn that a madman had slaughtered her bride-to-be daughter at a Long Island pharmacy until her plane landed at Kennedy Airport late Monday night.

She rushed back from her Jamaica vacation under a dramatic ruse — to spare her nerves, her husband lied and said that her son had suffered a seizure.

But she was told the horrific truth by officials who briskly ushered her to a private room at Kennedy that was packed with family and paramedics.

“I can’t believe my daughter’s gone! She was a wonderful person, so wonderful,” the grieving mother wailed at Haven Pharmacy yesterday, the scene of the bloodbath where a man shot and killed daughter Jamie Taccetta and three others in order to steal pills.

“He was so senseless! He could have stole the drugs and left everyone alone, just threw them in the back. There was no reason to shoot them,” she shrieked. She swore the fiend — whose chilling, execution-style killings were caught on surveillance video — wouldn’t be on the lam for long.

“We’re going to get you. Justice will be done,” she vowed. “He took away four lives. He took away a young girl!”

In a painful twist, Jamie, 33, was set to marry James Manzella in October. She’ll now be dressed in her wedding gown at her funeral Saturday. “She was so happy,” the mother said. At the mom-and-pop shop yesterday she lit candles and left a picture of her daughter at a beauty pageant when she was 7 years old.

“Oh, Jamie!” she said, sobbing and grabbing onto bars of the pharmacy’s window for support.

Manzella left a bouquet with a stuffed monkey and a note that said, “To Jamie, The best thing that ever happened to me . . . See you in heaven.”

Jamie’s ex-husband and two sobbing daughters also brought a bouquet of yellow, purple and pink flowers. Police scoured the area yesterday for the skinny, bearded gunman who first killed druggist Raymond Ferguson and cashier Jennifer Mejia and was stuffing oxycodone painkiller pills into his backpack when Taccetta and another customer, Byron Sheffield, walked in and were killed.

“He’s a coward,” said Jamie’s father, Ralph Taccetta.

“If he’s listening or if he’s looking: You’re a punk. You killed four people, you’re a punk. We’re going to get you, maybe not today, maybe not tomorrow, we’re going to get you and we’re going to do what needs to be done,” he said.

“I don’t want to hear that you’ve got a drug problem or anything like that because it doesn’t matter,” he added. “I really don’t care.”

The shop’s owner, Vinoda Kudchackar, and another pharmacist had taken the day off for Father’s Day. The two slain employees were filling in for them.

“I don’t think he’ll ever set foot in that store again,” said Kudchackar’s friend, Bill Simpson.

Investigators said they had received more than 250 tips yesterday, and had a suspect in mind — a local who’s a known drug addict.

Additional reporting
by Selim Algar, Kieran Crowley
and Josh Margolin