By Jill Smolowe and Liz McNeil
Updated June 04, 2012 12:00 PM

The day before Mary Richardson Kennedy took her life on May 16, she phoned estranged husband Robert F. Kennedy Jr. “‘You know me better than anybody in the world,'” he said she told him. “‘I was such a good girl.'” Days later, at Mary’s memorial service in Bedford, N.Y., Bobby sobbed recounting their final conversation. “I said, ‘I know. And you still are,'” he said. “She was the most perfect human being I ever met. She had these demons, and she didn’t deserve it.”

Missing from this emotional scene were Mary’s siblings. They had hurried to Bedford after learning their sister hanged herself with a rope in the barn on her 10-acre estate. Bobby, who the morning after the body was found worked out at a local gym, asked them to leave, says a friend of Mary’s. “They were also told they were not welcome at the funeral.”

The shocking suicide of Mary Kennedy, a woman married into a storied clan that has seen more than its share of untimely death, ensures that yet another generation of Kennedys will grow up shadowed by tragedy. Mary leaves four children, ages 10 to 17-and relatives feuding so bitterly that the two families had to go to court to decide where Mary would be laid to rest and two separate memorial services were held. Two days after the Bedford service, the Richardson family and some 200 friends gathered in Manhattan. But at this event, there was no Bobby, and there was no talk of lifelong demons. Instead there were only fond recollections of “the light and love that Mary brought into a room,” according to one attendee, and of her loving nature and positivity-until her marriage began to unravel.

Those dueling portraits of Mary cut to the heart of the painful question both sides now must grapple with: Why did this mother of four kill herself? A gifted architectural designer and welcoming hostess, Mary, 52, was universally seen as a giving woman devoted to her children, her friends, her husband, her charities and the Catholic Church. Her husband, 58, estranged since 2010, had only achingly kind words in his eulogy. “She was a genius at friendship,” he said from the pulpit. But, he added, “she had this sadness that kicked her and chased her.”

Was that sadness coming from within? Or was it a product of circumstance? In his eulogy Bobby talked about doctors being unable to figure out what medication she needed, that she “did everything she could” to fight that crippling sadness. “I know I did everything I could for her,” he went on. “And she knew that.”

But it is also no secret that for the last four years she’d been struggling to rescue her disintegrating marriage. “She was heartbroken,” says a neighbor. “She loved Bobby and wanted him to love her.” Another says, “Her identity was wrapped up with her husband’s. It was like she lost her sense of self.”

Mary Richardson met Bobby Kennedy through his sister Kerry, Mary’s boarding school pal from the time they were 15. Mary grew so close to Kerry that she often spent holidays with the Kennedys. “She fit in with the family so well,” says friend Henry Schleiff. Bobby’s mother, Ethel Kennedy, “loved Mary,” says Joan Kennedy, ex-wife of the late Sen. Ted Kennedy. Mary and Kerry later roomed together at Brown. When she married Bobby at age 34 aboard an environmental research vessel on the Hudson River, Mary was six months pregnant-and he was a father of two and just one month removed from his divorce from his first wife, Emily. Though she fought the move from downtown New York to Bedford’s country-suburbia, Mary threw herself into her and Bobby’s environmental causes and into parenthood. “She was such a great mom,” says a Bedford mother who recalls Mary seated courtside at all of daughter Kyra’s basketball games. “She wasn’t one of those moms on their iPhone.” When son Conor developed severe food allergies, Mary helped raise $35 million to establish the Food Allergy Initiative, which funds research. She still found time to be a generous host, often opening the family’s Westchester estate to games involving poetry or capture the flag. “The range of people who came was incredible,” says pal Peter Michaelis. “She always made sure there were lemonade and Oreos.” Adds his wife, Victoria, a Brown friend: “I’d say, ‘I have houseguests.’ She’d say, ‘Bring them!'”

All of that changed three years ago when Mary became convinced that mold in her aging house was exacerbating her kids’ allergies and asthma. Halting the guest traffic, she spearheaded a three-year renovation showcasing green technology. By the time she was done in 2010, she and Bobby were separated. “After the renovation, it was different,” says Victoria. “The marriage was unglued. Everything was quieter. She was taking sedatives to deal.”

As her husband and his family tell it, Mary battled depression long before her 1994 marriage or its later problems. “She struggled from the time I met her, when she was 15,” Kerry Kennedy, 52, told PEOPLE. Others disagree. “Battling demons? That’s hyperbolic language,” says Carole Radziwill, a Mary friend (and the daughter-in-law of Jacqueline Kennedy Onassis’s sister Lee). “I didn’t see anything close to that.” Adds another friend: “Mary did not have a history of depression. She became a troubled person because of the divorce.”

Whatever their origin, her issues began to play out in public. In 2007 a local paper, the Journal News, reported that twice Bobby called police, worried that his wife might hurt herself. In 2010, three days after he filed for divorce on May 12, Mary was arrested for drunk driving. That same week police were summoned two times for “domestic incidents.” During one, Mary alleged that Bobby had been “abusive” to her and her children; he, meanwhile, told police she was intoxicated and “acting irrational.”

Still, she was determined to hold her marriage together. “Mary didn’t believe in divorce,” says Michaelis. As the proceedings grew nastier, friends say she began drinking more. The following summer, “Mary was told she wasn’t welcome in Hyannisport,” says a friend, referring to the Kennedy family compound. “As a result, Bobby was told he couldn’t come into her house.”

As last Christmas approached, she held out hope for a reconciliation, even though by then Bobby was in a relationship with actress Cheryl Hines. (Hines, who stayed in L.A., issued a statement through a friend that “she sends her thoughts and prayers to the family.”) Mary believed her kids were going on a ski vacation with Bobby-and probably Hines-yet she told friends she would be going. “It was a story she was telling herself,” says a friend. Instead Mary spent the holidays tearfully telling Michel Rossignol, owner of Bedford Village Pastry, “It’s not easy to divorce a Kennedy.”

It got worse. A source says that not long ago, Bobby phoned Child Protective Services. Their children-Conor, 17, Kyra, 16, Fin, 14, and Aidan, 10-were moved from her house to his. “I know Bobby was concerned about the kids,” says Michaelis. But it’s unclear why the children were taken at that moment. Mary joined Alcoholics Anonymous and began counseling after her first DUI. (A second charge, soon after the first, involving prescription medication was dismissed.) Mary was restricted to supervised visits and wasn’t sure she could count on those. “That was the worst blow,” says a friend.

In recent weeks, though, it seemed like she was rallying, including an appearance at a pal’s 50th birthday party. “She seemed to be in fairly decent shape,” says Michaelis. “She was thrilled with her kids’ successes in school.” But with the children living away, Mother’s Day, May 13, could have been unbearable. “I can’t imagine how it was for her,” says a Bedford friend. “I was trying to get her to come for dinner. She said she didn’t want to come but that she was going to ‘take baby steps’ toward going out. That was the last thing she said to me.”

On May 16 Mary was laid to rest near the Kennedys’ Hyannisport compound. The burial location was in accordance with the wishes of her children. “They are doing what they are supposed to be doing,” says Kerry. “Sometimes they are happy telling great stories about her and jumping in the ocean, and sometimes they are in tears.” As they grow up, they will have to reconcile the two portraits of their mother. “She truly believed in the goodness of people,” says Carole Radziwill. “In the end that was her undoing.”