From PEOPLE Magazine Click to enlarge
She has always been one of Hollywood's most respected—and respectable—stars. So in recent years, the coarse public behavior of other celebrities has grated on Reese Witherspoon. At 2011's MTV Movie Awards, the actress, 37, derided the boorishness of reality TV. And while lunching with pals in Los Angeles a while back, she had choice words for Lindsay Lohan and others who land in hot water behind the wheel. "She was saying, 'How do they keep getting in so much trouble? Get a driver!' " says an eyewitness. "She hates that her daughter is living in a world where these girls are role models."

Of all the parts Witherspoon has played, it is her most cherished: that of a churchgoing, Oscar-winning mom of three with a perfectionist streak. "She definitely has a certain image she likes to put out there," says a friend. That straight-arrow reputation veered off-course on April 19, when she and her husband of two years, Hollywood talent agent Jim Toth, were arrested in Atlanta following a night out. A collective sense of shock—not Reese!—and disappointment—not Reese—spread as quickly as the arrest details: Toth, 42, was charged with driving under the influence; Witherspoon was charged with disorderly conduct after allegedly demanding of a police officer, "Do you know my name?"

Witherspoon immediately issued a public apology, noting that she was "deeply embarrassed" by the incident, and less than three days later was back in red-carpet mode, flashing her dazzling smile at the New York City premiere of her new indie drama Mud. Privately, though, friends say she is humiliated and worried about the fallout for her reputation, her marriage and especially her kids, Ava, 13, Deacon, 9, and Tennessee, 7 months. It was "hard for her to be away from them" after news of her arrest broke, a source in her circle says of the star, who flew to L.A. to reunite with her older children before returning to the Atlanta set of her drama The Good Lie on April 29. "She's worried about how they'll be treated." Already dealing with the stress of a new baby, an ailing father and career pressures, Witherspoon is taking the criticism hard: "It's been awful for her," says her friend. (Like others in this story, the friend spoke to People anonymously out of concern over upsetting the very private actress.)

Even those who know her well are baffled by her behavior the night of her arrest. Yes, the incident was "out of character" for Witherspoon, though "not unimaginable," notes her friend. "She's a fun girl who likes to let loose every now and again. What's shocking is that she didn't rein it in enough to keep out of trouble."

The Nashville-bred star, who broke out at age 15 in 1991's The Man in the Moon, shares that side of herself with family and close friends. "Reese is a southern sorority girl to her core," says a source who has known her for many years. Just 23 years old when she married actor Ryan Phillippe, now 38, "she got discovered young, got pregnant and married young and has no real connections to the real world," says the source. "With her, what happens in public and in private is very different. She does like to drink. She's actually the real girl next door, not the cliché girl next door."

But she's rarely prone to excess and sensitive about her image. However, when it comes to men, "she likes guys with an edge," a friend of Toth's says of the actress, who split from Phillippe in 2006 due to her frustrations with his carousing. "I'm not interested in the fallacy of the Hollywood relationship: 'We have perfect children who never cry; we never have problems; we never argue,' " Witherspoon told PEOPLE in 2002. "That's just not true. We're normal people with normal problems."

As for Toth, an executive at industry powerhouse CAA, "Jim's like, 'I'm gonna show you every day what a good partner is, what a good person is. I'm going to take care of you,' " she told Elle last year. Toth "was on his best behavior for about a year after he and Reese first started dating," says the person in Witherspoon's circle. "But things started to change last year. Jim gets very loud and obnoxious when he drinks, and it's embarrassing for Reese." Adds an agency source: "Jim has always been a big social drinker. He's pretty shy deep down, so I think drinking helps him socialize. It seemed to most of his friends like he was hiding this part of himself from Reese at first, but I think he's totally himself with her now, which means he can be a party animal again."

Witherspoon, meanwhile, has had her hands full taking care of baby Tennessee—"seriously, this child stole my brain," she told Britain's Red magazine—and the challenges of maintaining an A-list career: Her last few studio films, including This Means War and Water for Elephants, have fared poorly at the box office. She also has coped with family drama surrounding her father, John, a retired physician who has long been separated from Witherspoon's mother, Betty. Last May the actress attended a closed-door hearing in Nashville, where Betty—claiming that John is in a weakened mental state—petitioned to have John's marriage to a woman named Tricianne Taylor annulled. "She's incredibly close to her parents," a friend told PEOPLE at the time. "She looks up to her mother so much, and to see her going through this must be very difficult for her."

Now the actress is leaning on her mom as she endures her own tough time. Those close to Witherspoon and Toth say the couple's arrests in Atlanta—they are due in court on May 22, where they will both likely face fines and community service—have served as a powerful wake-up call, even as they remain committed to each other. "This isn't going to break up their marriage," says her friend. "It was a really bad decision on both of their parts. Trust me, they're evaluating that and will make damn sure it doesn't happen again."