EVAN DORSEY was a Villanova student and Danielle Cattie attended Immaculata when they met at a mixer more than 15 years ago.

Later, they had a child together - Ebony Dorsey - but never married.

Cattie left school and now lives in Ambler, works at a bar and, according to police, has a cocaine habit.

Dorsey, of Medary Avenue in West Oak Lane with his grandmother, who recently died, went on to teach computer science at Villanova.

Cattie, 34, and Dorsey, 36, shared a great love for their 14-year-old daughter, an honors student at Wissahickon High School, Cattie and neighbors of Dorsey's say.

But now they share a devastating grief - at the vicious sexual assault and murder of their child, allegedly by Cattie's boyfriend and purported drug supplier.

Yesterday, Cattie spoke exclusively with the Daily News - mainly about her life and her loss, but also lashed out at her daughter's alleged killer, calling him a monster.

"People need to realize, regardless of anything that has been said, he [Mark O'Donnell] is the monster," said Cattie, who otherwise said she could not discuss the pending case. "We've been together for four years and there was no way to tell that this was going to happen."

O'Donnell, 48, who lived in an apartment in Plymouth Meeting, had smoked a "significant" amount of crack at Cattie's house last Thursday night, according to authorities, before he allegedly strangled Ebony early Friday and allegedly sexually assaulted her while she was babysitting his 4-year-old daughter.

O'Donnell, who is married, told authorities he'd taken Ebony to his apartment to baby-sit his daughter Kyra while his wife was away, and came home in the predawn hours to find her changing the child's diaper and flew into a rage and attacked her. He said he thought she was molesting the child - an allegation that authorities say is unfounded.

He placed her body in a blue tub in his bedroom and later concealed it under leaves at a relative's house in Blue Bell, according to authorities. Police found Ebony's body Sunday.

According to an affidavit of probable cause, police said Cattie told them she had been "snorting cocaine for the past several years and more frequently over the past several months." Police said Cattie told them O'Donnell converted the powdered cocaine into crack and smoked it.

Authorities said Cattie did not report Ebony missing until Friday night, although the girl had been absent from school that day.

"There was never any reason for any of us to feel" that Ebony shouldn't live with her mother, Cattie said.

"Ebony was happy where she was," Cattie said. "She didn't have any problems at the house."

Evan Dorsey could not be reached yesterday for comment. Cattie said O'Donnell's "drug use had nothing" to do with Ebony.

"She was just a bright star, full of life. Just a happy child. She loved school, she was very proud of her accomplishments and her grades," said Cattie, who has three other children whom Ebony helped care for. "But she enjoyed herself."

Cattie disputed the notion that Dorsey was an absentee dad.

"Evan was the picture-perfect father," Cattie said. "He was in constant contact" with Ebony, picking her up on weekends and bringing her to his house every summer to live with him and his grandmother.

"He may not have raised Ebony," Cattie said, but "he was up on her school work, would get her school clothes. She would spend every summer with him."

The last call on Ebony's cell phone was from Dorsey, who called her every morning to wake her for school.

"Ebony was his only child," Cattie said.

"It's one thing to have a child taken, but this is unbearable," Cattie told a reporter.

"Yes, a bad decision was made, but that doesn't change the fact that I loved my daughter.

"Ebony lived with me all her life, outside of a period when she was 2 or 3 when she lived with Evan," Cattie said, holding back tears.

"I just miss my baby."

A Dorsey sister-in-law in Maryland also scoffed at the idea that Dorsey was an absentee parent, saying "nothing could be further from the truth."

Neighbors on Medary Avenue near Garnet Street also painted Evan Dorsey as a loving father.

"He was what you call 110-percent daddy," said neighbor Ella Turner.

"She [Ebony] was so respectful, so mannerly. Her great-grandmother really loved her,"Turner said.

"Her father was into her life from the day she was born until the day that she died," said another neighbor, who asked not to be identified.

When Ebony's great-grandmother couldn't participate in block cleanups anymore, she sent Ebony out to take her place, the neighbor said.

A nondenominational funeral service will be held Saturday at Wissahickon High School, with a viewing from 8 until 11 a.m., according to the Emil J. Ciavarelli Family Funeral Home.