Terri, a 44-year-old substitute teacher from Alabama, said her manipulative mother-in-law makes her life a living hell.
"Our son, her grandson, gets whatever he wants from her even after we tell him no," said Terri, who didn't use her last name for fear the monster-in-law would recognize her. "The holidays are spent at relatives' houses with her talking bad about me behind my back."
Worst of all, said, Terri, her mother-in-law enables her husband by undermining efforts to get him to cut back on the booze.
"I tell him he needs to slow down," Terri said, exasperated. "Then the next thing I know, she goes out and buys him a bottle of Crown Royal for Christmas."
"This has been going on for 16 years now," she said. "She has even tried to get my husband to divorce me. I do not feel comfortable around her because when she pretends that she is behaving, she is scheming."
Terri is not alone.
A recent survey published by the website Gurgle revealed that 7 in 10 women say that their mothers-in-law are the biggest problems in their lives, questioning their parenting skills, barging into their homes and spoiling their sons and grandchildren.
Top complaints were criticism of child-rearing (39 percent); interference in daily life (23 percent); babying their sons (20 percent); spoiling the grandchildren (11 percent) and turning up at the house uninvited (7 percent).
In another study published last year by British psychologist Terri Apter, two-thirds of women complained that they had suffered long-term because of frictions with their husbands' mothers.
She described her two decades of research in the 2009 book, "What Do You Want From Me?"
Other studies show living with your mother-in-law can be downright dangerous.
A 2010 study from Harvard Medical School revealed that Japanese women -- who have a lower risk for cardiovascular disease than Americans -- were three times as likely to have a heart attack if they shared quarters with their husband's mothers.
In the end, it had little effect on the men's health, but the wives suffered coronary artery disease and a large number died of heart attacks.
Gordon Ramsey Has Mother-in-Law Problems
Celebrities have mother-in-law issues, too.
Comedian Sunda Croonquist was unsuccessfully sued by her mother-in-law, Ruth Zafrin, for making her the butt of too many jokes.
And celebrity chef Gordon Ramsey has had a public feud with his mother-in-law, Greta Hutcheson, who threatened to cut ties with his wife, Tana, after he fired her husband and former business partner Christopher Hutcheson.
And the most stressful time for confrontations with in-laws is inevitably the holidays.
"There are two reasons, the unexpected visit and the gift-giving," said Beverly Freid, founder of the website Mother-in-Law Stories.
Her site gets 75,000 visitors from all over the world each month, 80 percent of whom are women.
Female readers report tactless gifts: a liposuction surgery gift certificate, pre-paid legal service for a divorce, samples from make-up counters, toilet paper, an outdated calendar, and maternity clothes for the daughter-in-law who is not pregnant.
Step children in blended families are often ignored entirely.
Others complain that mothers-in-law ask them to "step out of the picture" when it's time for a family Christmas card shot. Some were even asked to step out of their own wedding photos because "It's family only," said Freid.
She advises daughters-in-law to bring up differences early.
"Communicate and seek counseling if it's just not resolving, especially if you hope to have a long and happy life," she said. "You'll put up with it for a long time if you don't nip it in the bud."
For Terri, Christmas is always a booze fest, one fully sanctioned by her mother-in-law.
"Her husband is loud and obnoxious," she said. "At any moment if something isn't going right, he will go off and start cursing whoever he feels deserves it."
When her son, now 12, was born with health issues that eventually resolved, her mother-in-law told the world that her grandson had been born sick "because I did something wrong during my pregnancy," said Terri.
The woman may be generous -- buying her son a new car -- but mean. The couple was just about ready to close on a new house, and the monster undermined the sale.
"She had nothing to do with it, no money down," said Terri. "She just wants to be involved. I was livid."
When the couple went into marriage counseling a few years ago, mother-in-law joined in. "My husband invited her," she said. "They are close."
Mother-in-Law Kills Christmas Cactus
Cheryl, a 40-year-old mother of four from Fort McCoy, Fla., lives less than a mile down the street from her "self-centered" mother-in-law, but the family rarely celebrates the holidays together anymore.
First, there was the Christmas when she was called a "fat ass" in front of the entire family. Then the in-laws played favorites, ignoring her two older children from a previous marriage.
Now, Cheryl says she has decided to cook Christmas dinner in her own home, and her mother-in-law has shunned her.
"Don't get me wrong, I do invite her," said Cheryl. "It is her choice."
One year, her mother-in-law dropped off holiday gifts when Cheryl's family wasn't home. Rather than leave them in an open space on the covered porch, the vengeful mother-in-law dumped them on top of Cheryl's beloved Christmas cactus.
"I cried and cried," she said. "She knew it had come from my grandmother who died."
"I really don't know why she is like this," said Cheryl. "I think it's jealousy. I am at home with the kids and have the life she always wanted."
Jealousy works both ways, according to Martha Chabinsky, a Kripalu yoga teacher from Amherst, N.H., who is also a mother-in-law.
"The most important and hardest thing is not to take anything personally," she said. "A young woman can be intimidated by the relationship you have with your son, just by the fact that he is your son. You are the closest woman to him, and some young women are threatened by that."
Her advice is to treat a daughter-in-law as you would a daughter.
"Listen, be compassionate, speak your mind when you feel it's necessary, don't make assumptions, and show by example how to take care of yourself," said Chabinsky, 57, who has three sons.
But she also warns about "kowtowing" to a daughter-in-law's demands, "if they seem out of line."
"Doing so just makes her feel that she has power over you," she said. "No one has power over anyone here....they should communicate, not make assumptions, and keep strong boundaries."
Her daughter-in-law, Lisa Appleyard, 36, of Bethel, Conn., who has a positive relationship with Chabinsky, agrees.
A good mother-in-law is someone who "can listen without judgment and who is forgiving when mistakes are made."
To find out how to cope with your in-laws, see Gurgle's mother-in-law guide.