June 21, 2010 -- "Little House on the Prairie" is loved the world over for its quaint family drama.
Alison Arngrim, who played Nellie Oleson during the series' original seven-year run, still gets e-mails from "Prairie" fans who say the show became their substitute family during their "horrible childhoods."
"Well, it was the same for me," Arngrim, now 48, told ABCNews.com.
In her new book, "Confessions Of A Prairie Bitch: How I Survived Nellie Oleson And Learned To Love Being Hated," Arngrim reveals how she was sexually abused as a child, and how the role of bad girl Nellie helped her to heal. She also shares behind-the-scenes tales of one of the world's most beloved series.
Arngrim writes that she was abused by a family member for nearly three years starting at age 6. The abuse made her, an already diminutive girl, even more shy and withdrawn.
That changed when Arngrim got the part of scheming brat Nellie Oleson at age 11.
"People were suddenly intimidated by me," Anrgrim said.
Other times, she was reviled like her character. Since age 11, Angrim has been called "bitch." She's been spat on, pelted with garbage and beaten up.
But thanks to Nellie, Arngrim found an outlet for the rage that had been building since her abuse -- a secret she kept from her parents until her twenties.
"When you're sexually abused you have a lot of anger," she said. "Usually victims turn the pain and rage on themselves. So to have an outlet where one could express this anger outwardly and openly was a fantastic opportunity."
Arngrim is grateful for Nellie. "Instead of her ruining my life, she gave me my life."
Coming from a show business family -- her father, Thor Arngrim, managed Liberace and her mother, Norma Macmillan, provided the voice for Casper the Friendly Ghost and Gumby -- Arngrim got to experience "normal family life" on the "Little House" set.
Michael Landon, who played Charles "Pa" Wilder and produced the series, was very much the set's father figure.
Michael Landon Less Than Angelic
"He saw to it that the rules were obeyed," Arngrim said. "We said 'yes, sir' and 'yes, ma'am.' We had to know our lines. We were held to a higher standard."
At the same time, Landon was nothing like the prairie dad he played.
"He was divorced and married several times," Arngrim said. "He lived in Bel Air and Malibu, attended the Playboy Jazz Festival, drove a Ferrari, smoked and drank. He had this wild sense of humor on set that really shocked people."
For one thing, he had an "unsaintly" habit of showing up without underwear on the set.
Nellie and her nemesis Laura Wilder may have scrapped on screen, but off camera Arngrim was best friends with Melissa Gilbert, who played Laura.
"I had an intense, wonderful friendship with Melissa, who became a sister to me," Arngrim said.
Melissa Sue Anderson, however, who played Gilbert's on-screen sister Mary, wanted nothing to do with Gilbert and Arngrim.
"Melissa and I were wild and fun loving," Arngrim said. "Melissa Sue just looked at us and shook her head."
Arngrim's other best friend on the set was Steve Tracy, who played her on-screen husband, Percival Dalton, toward the end of the series. When Tracy contracted AIDS and went public with his diagnosis in the mid-1980s, Arngrim stood by him. She began volunteering for AIDS Project Los Angeles and speaking about the disease.
"Back then, people were even terrifed to have a presentation about the disease, but they'd say, 'Oh, it's the lady from "Little House."' I got into places and talked about HIV and AIDS where they would never have someone speak," Arngrim said.
Tracy died in 1986, but Arngrim continued to be an activist. Through AIDS Project, she met her husband Robert Paul Schoonover, who plays in the Southern California band Catahoula, and they've been married 17 years. She also got involved with the National Association to Protect Children.
While fighting to change a California law that allowed incest offenders to leave jail early, Arngrim decided to go public with her own childhood sexual abuse in a 2004 interview with Larry King.
"I remembered Steve going public," she said, "and thought the shoe is on the other foot now."
That opened the floodgates for Arngrim, who began touring her comedic one-woman show "Confessions of a Prairie Bitch," in which she talks about her years playing Nellie.
Find out what happened to some of Arngrim's fellow cast members since the series ended.
Melissa Gilbert/Laura Ingalls:
Adopted soon after her birth, Gilbert grew up in a Hollywood family. After starring in dozens of television commercials, she landed the role of Laura Ingalls on "Little House" at age 8. Michael Landon became a surrogate dad to her when her own father died.
By her late teens, Gilbert rebelled against her perfect prairie girl image. She describes her battles with drug and alcohol abuse and co-dependence on men in her 2009 memoir "Prairie Tale."
Gilbert, who was once engaged to Rob Lowe, also dated John Cusack, Billy Idol and Tom Cruise. In 1998, she married actor Bo Brinkman and they had a son, Dakota. The marriage ended after four years. Since 1995, she's been married to actor Bruce Boxleitner and they have a son, Michael, named after Landon.
Known as the "Queen of television movies and mini-series," Gilbert, now 46, has starred in over 45 of them since the mid-'70s. The president of the Screen Actors Guild for two years, she can also be seen touting hair care products on late-night infomercials.
Michael Landon/Charles Ingalls:
Landon was a fixture on the small screen. In 28 years, he starred in three successful television series: "Bonanza" in the '60s and early '70s, "Little House" in the '70s and early '80s, and "Highway to Heaven" in the '80s.
He married three times and was father to nine children and stepchildren. In April 1991, he was diagnosed with an inoperable form of pancreatic cancer. Appearing on "The Tonight Show" with Johnny Carson, he asked his fans to pray for him. He died July 1, 1991 at age 54.
Melissa Sue Anderson/Mary Ingalls:
Anderson won the role of Mary at age 11 after appearing in several television commercials and guest starring on "The Brady Bunch." She left "Little House" in 1982 and appeared in a few television series, including "The Equalizer" and "Murder, She Wrote."
After a short romance with Lorenzo Lamas and Frank Sinatra, Jr., Anderson, now 47, married television writer and producer Michael Sloan. They have two children and live in Canada.
Anderson has continued to act occasionally, mostly in television movies. Her most recent role was playing the first lady in the 2006 NBC miniseries "10.5: Apocalypse."
Katherine MacGregor/Mrs. Oleson:
MacGregor is still beloved for her comedic role as Mrs. Oleson on "Little House."
"That woman's a genius," Arngrim told ABCNews.com. "She's absolutely hilarious."
Now 85, she retired from acting after the series ended. Arngrim said she still takes in stray animals and people and "she's still bossing everyone around."