Updated 11/25/11 – 11:09 a.m.

CHICAGO (CBS) — Maggie Daley, the beloved former First Lady of Chicago and wife of former Mayor Richard M. Daley, has died. She was 68.

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Mrs. Daley, who had been diagnosed with breast cancer in 2002, died Thursday night around 7 p.m. at home. Her husband and her three children were by her side.

CBS 2 Chief Correspondent Jay Levine reports, she had been alert for most of Thanksgiving Day and she passed peacefully in the early evening.

Mayor Rahm Emanuel released a statement on Thursday night, saying, in part: “Tonight we grieve for the Daley family. Chicago has lost a warm and gracious First Lady who contributed immeasurably to our city. While Mayor Daley served as the head of this city, Maggie was its heart.”

The family announced on Friday that a public visitation will be Sunday from noon to 10 p.m. at the Chicago Cultural Center. The funeral Mass will be on Monday at 10:30 a.m. at Old St. Pat’s church.

“Much of the beauty of this city is due to her,” said political analyst Thom Serafin. “She grew larger than life. She seemed to be the hovering craft over all of us.”

Members of the Daley family were seen going in and out of the family’s home on Thursday night, but the former mayor remained secluded.

The Daley family issued a statement through spokeswoman Jacquelyn Heard, saying, “The mayor and his family would like to thank the people of Chicago for the many kindnesses they’ve shown Mrs. Daley over the years, and they appreciate your prayers during this time.”

She was a fighter, a woman whose embrace of the city she loved will live as her legacy.

Word of Maggie Daley’s death spread quickly among people out with friends and family in Chicago over Thanksgiving.

Bishop Walter Armstrong was eating with a crowd of other customers at the White Palace Grill when they heard the sad news.

“Shocked, surprised; but, then, I kind of had anticipated it, since he had cancelled all of his appointments and they had moved up the wedding,” Armstrong said. “So, I kind of figured that she was in a much worse position than they were really saying.”

Chicagoan Michael Hildner said, “The Daley family really kind of lived, I feel like, with the city of Chicago. They shared themselves.”

Mrs. Daley immersed herself in the mission of improving her city and helping those around her.

Supporters said they’ll remember her determination to push through her pain.

“So in the midst of our suffering, we still have to keep on working,” Armstrong said.

Maggie Daley was the driving force behind the group “After School Matters” – an arts, sports and technology program for students.

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The organization said in a statement that “Chicago’s teens have lost their strongest voice and champion.”

Gov. Pat Quinn said in a statement, “The State of Illinois lost a great treasure. Maggie Daley was a woman for all seasons who treated Chicago residents like family and served up hope and inspiration wherever she went. … Our thoughts and prayers are with the entire Daley family. The people of Chicago and Illinois now mourn a great loss, but we remember the legacy of grace and compassion that Maggie left.”

The former Maggie Corbett, grew up in Pittsburgh. She was a popular student and high school basketball player. At the University of Dayton, she was farewell queen.

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On March 25, 1972, she married Richard M Daley, right after he was elected to the Illinois State Senate. She was with him every step of the way as he rose to the mayor’s office–ultimately becoming the city’s longest serving chief executive. Mr. Daley, who would often get emotional when talking about his wife, once called her the family’s greatest campaigner.

It was the 2002 diagnosis of metastatic breast cancer that would really test her resolve.

Her first public appearance after that news set the tone.

“I feel good and I am so grateful, really beyond words, for the good wishes and the kindnesses, and the concern and especially the prayers,” she said. “They mean an awful lot. And, I’m just enormously grateful.”

So began a battle with the odds stacked against her; beating those odds year after year, to the delight of her doctors.

Through it all, Maggie Daley remained a proud partner for the mayor and a devoted mother to her children, Nora, Patrick and Lally.

There was suspicion that things weren’t going well for Mrs. Daley when Elizabeth “Lally” Daley moved up her wedding plans from New Year’s Eve to her birthday last Thursday, due to concerns about her mother’s health. Lally married her fiancé Sam Hotchkiss last week so that her mother could attend and fully enjoy the wedding.

Mr. and Mrs. Daley both walked Lally down the aisle, as she wore her mother’s wedding dress.

Then, on Wednesday the former mayor announced that he was canceling all public appearances for the rest of the year, including a one week engagement as visiting fellow at the John F. Kennedy School of Government at Harvard University.

Although the Daley family said the wedding date was changed because they wanted celebrate at a time Maggie was well enough to enjoy it, a source close to the family said Wednesday that Mr. Daley’s decision to cancel his travel plans was “indicative of Maggie’s condition.”

During her nearly decade-long treatment, she maintained a significant public schedule as Chicago’s First Lady.

She was co-founder of Gallery 37, later renamed After School Matters, which educates and employs young people in the arts and a variety of other out-of-school activities.

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She is survived by her husband and three children. Her 33-month-old son, Kevin, died of complications related to spina bifida in 1981.