If you think your mother-in-law is a nightmare, spare a thought for the woman who was forced to do a DNA test on her child.
And when she got the DNA results - the deluded screaming grandma still refused to believe the paternity test.
In TLC show I Love A Mama's boy, Nancy nastily makes it her mission to split up her son Robert and his wife Kristy, despite the fact they have two kids together.
Nancy, who only sees Kristy as a threat to her strangely close relationship with her 28-year-old son, maliciously knocks down her daughter-in-law, 26, at any given opportunity.
But the 49-year-old, from Hesperia, California, really crosses the line when she devises a crackpot theory that her granddaughter, Kimi, is not related to her.
Claiming her son was "trapped" and that he wed accordingly, Nancy doesn't approve of Kristy and claims she cheated on her son with another man.
Nancy, who doesn't want her son's child to be biologically his, says: "Now I have to start praying for the DNA results so my son can know the truth and leave her ass and come home with me."
Kristy says: "I don't even want my kids around you because you don't think that's your grandchild. I don't know how you're going to treat Kimi as you don't think she is yours."
Robert is forced to get in the middle of his mum and wife when things get heated - with Kristy accusing Nancy of trying to sabotage their family.
It turns into a huge shouting match, with Robert's aunt and brother getting involved, which only fires up Nancy even more.
"Get used to your life without your son," says Kristy as she storms out of the house with Robert, only for his mum to reply: "If you leave I will beat her ass."
Finally seeing his mum for what she is, Robert admits she has gone overboard and he has decided to step up to confront her.
But Nancy says: "Kristy is so evil. she thinks she is winning taking my son away. That's not happening any time soon."
The conflict isn't over as Nancy drives over to the family's home and starts frantically beeping her horn outside, prompting a row on the driveway.
Choosing his wife, Robert confesses: "It almost feels like I'm breaking up with my mum. I'm choosing my family over her. I can see the damage I'm causing Kristy and my family and I don't like that feeling."
Kristy goes through with doing the paternity test, but feels sad her innocent daughter is involved in "something so ugly".
After anxiously waiting, Kimi discovers gets the DNA test results, which confirm her daughter and Robert have a 99.99999% genetic match.
They believe this may finally be the end of the saga, but it certainly isn't as Nancy still refuses to accept the incredibly conclusive result.
Latching on to the miniscule 0.00001% chance that Robert is not the father, Nancy asks: "Why can't it be 100%?
"Anyone can pull this s*** out of the internet. These results look like they are fake."
Screaming Nancy is insistent that Kristy has "sabotaged" the results and even asks to speak to tabloid talk show host Maury Povich.
A furious Kristy says: "I'm so over it at this point. I'm so done with her trying to tear apart our family. I can't deal with it any more.
"I'm not surprised at what Nancy does at this point. There is no limit as to how low she will go.
The couple had no choice but to distance themselves from Nancy at the end of the season.
