Q: My mother and I had a fight. I apologized, but now she won’t stop yelling that I am a terrible daughter for threatening to move her to a nursing home. Am I horrible?
A: No, you are not horrible—and I know exactly how you feel because my father was so difficult we had to threaten him with "Shady Pines" frequently. After a year of caring for my parents by myself and having every caregiver I'd hire quit after a couple days because my father was so mean, I finally found "Amazing Ariana". She was so great that after a month of training her I felt confident enough to fly back home. Then, I only had to hear about my father's antics—several times a day.
Ariana put up with so much, but one time she was driving my father somewhere when she just had it with his meanness. She decided to drive him over to the nursing home and said, "OK, I've had it--I quit! Go on in—they're waiting for you." She said my father was so dumbfounded he didn't know what to do, but then he turned sweet as pie apologizing again and again for his nastiness. She got several weeks of good behavior out of him that time, but unfortunately when he figured out she was just making idle threats the technique didn't work anymore--darn!
So, in lieu of idle threats (or even real ones), be sure to discretely make sure your mom's doctors know about the nastiness so all medical reasons for the behavior can be ruled out. She could have chronic pain that is making her irritable, or depression which is common in the elderly, or her medications could be adversely affecting her, or she could be starting to get some form of dementia such as Alzheimer's (which makes up 65% of all dementias) that can distort reasonability. I bet you are going to say that the doctors said there is nothing medically wrong with your mom. I hear that all the time.
I know, I took my father to several doctors who said they couldn't find anything wrong with him because he'd act so darling and sane in front of them. I was astonished that he could act so charming when he needed to. Finally, I stumbled upon a neurologist who specialized in dementia who showed me the "Ten Warning Signs of Alzheimer's", which is when the light bulb went on for me. What was happening was that my father was addicted and trapped in his own bad behavior of a lifetime and his habit of yelling to get his way was coming out intermittently distorted because of the beginning of Alzheimer's and causing "over-the-top" behavior.
After extensive testing my father was finally diagnosed properly and given medication to slow down the progression of the Alzheimer's, an anti-depressant, and medication to help smooth out his moods (boy, I wish we'd had that 50 years ago). Now I am not saying he turned into an angel, I am just saying we didn't need police intervention any longer—really!
And since my father's dementia was just starting, we were able to use some behavior modification too, which is simply rewarding good behavior and never rewarding bad behavior. So when your mom is being mean say, "Mom, I love you, but I won't allow you to speak to me that way. When you can talk nicely, I'll be right back to help you", and then leave the room. Don't get into an argument--calmly set clear firm boundaries. If you do this every time she is difficult, she will soon realize that honey catches more flies than vinegar. And when your mom is nice, be sure to give her lots of physical and verbal affection to reinforce the behavior. With my father, we also learned that the bribe of vanilla ice cream worked like a charm to get him into the shower—even as he swore a blue streak that he'd just taken one (over a week ago).
And since it sounds like you are overwhelmed, I must tell you how great Adult Day Care may be for your mom, which would give you a much-needed break. It is so important that you get regular respite and that you put your health first so you don't get sick from caregiver stress, which happens far too often. Be sure to get your yearly physical, mammogram, and all your tests on time. I know what I am talking about, because unfortunately I didn't take care of myself during my caregiving journey and I developed invasive breast cancer.