Judy Diaz-Sierra and Emerita De La Pena had been inseparable since the days they became friends in a Manhattan high school more than a decade ago.

It took an act of terrorism to separate them.

De La Pena of Briarwood and Diaz-Sierra of Bay Shore were administrative assistants for Fiduciary Trust, on the 90th floor of the south tower, when terrorists struck. De La Pena is presumed dead; Diaz-Sierra’s body was recovered Oct. 13 and identified Jan. 18. They were both 32.

Ron Sierra spoke to his wife’s best friend, known as Emy, shortly before the first plane flew into the north tower. “Emy was planning her daughter’s birthday party, and we were discussing that,” he said.

The conversation was interrupted by one of De La Pena’s co-workers who said there had been an explosion in the building and they had to evacuate. “I didn’t want to contact my wife because the priority wasn’t for her to answer the phone, but for her to leave [the building],” Sierra said. “And I knew Emy would grab her and get out of there.”

Friends since their days at Julia Richmond High School in Manhattan – from which they both graduated in 1986 - De La Pena chose Sierra to be the maid of honor at her wedding in 1997, and Sierra returned the favor two years later.

Sierra’s husband compared his first meeting with his future wife’s friends, Gabriel and Emerita De La Pena, to meeting her parents for the first time: nerve-racking.

“They were very quiet and very reserved,” Sierra said. “They were meeting someone new in Judy’s life, and they were looking out for her best interests.”

A coin-operated laundry in Brooklyn was the site of Ron Sierra’s first meeting with Judy Diaz. Surrounded by the rumble of dryers and the smell of detergent, the two exchanged pleasantries, he said. They began dating in 1993, and were married six years later.

The day of their wedding, Sierra and his wife closed on their first home in Bay Shore. Looking forward to expanding their family, “Judy’s aspirations were to be a mom,” her husband said. But she also liked to stay in shape. Sierra remembered coming home and seeing his wife repping away on abdominal crunches or pedaling her stationary bicycle in front of the television. “She worked out as often as she watched television,” he said.

Gabriel De La Pena remembered the first time he saw his future wife typing away, with her hair tied back, at the New York City Public School Construction Authority, where the two worked in 1992. “Someone told me that I had to see this new girl that they just hired,” he said. “I thought she was beautiful. I was impressed right away.”

Emerita De La Pena, who was working toward a bachelor’s degree in education at St. Francis College in Brooklyn, was “a full-time mom, employee, wife and a part-time student,” her husband said. After returning to the couple’s Briarwood home at 8 p.m., she’d whip up a helping of rice, beans and steak - her husband’s favorite - and spend time reading to their daughter, Daniella. “She was an excellent mother,” her husband said.

The couples vacationed together several years ago in Florida, first at Disney World and later driving down to Miami, Sierra said. “Whenever Judy and I had something in mind, whether it was a show, or vacation, we’d always think of Emy and Gabe.” Whitewater rafting excursions, barbecues and Broadway shows are among Sierra’s memories.

Ron Sierra said he has found comfort in the fact that his wife was not alone Sept. 11.

“It’s sort of comforting that they were both together,” he said. “They were a great team.” - Nick Iyer