We have never gotten along, but it's worse now that she's older and needs more care. I am the only living immediate family left, we lost my brother to colon cancer in 2012 and I brought her to my home to live with me as she had been living with him in an old mobile home 17 miles away. If she doesn't get her way or doesn't want to do what I ask she threatens to call the police, or threaten to take me to court for abuse. The more I do for her the less she does for herself, she no longer gets dressed, combs her hair, washes, etc. Frequently she forget to take her heart and blood pressure medicines. She says I make things up, denies doing things she has done or said, I have a vivid imagination and laughs at me. She perfectly fits the Narsisstic Mother profile. She says she hates it at my house but won't leave always has excuses as why she can't, too much money for rent, etc. I get to the point I'm so frustrated I stop speaking and shut down and won't do a thing for her. Nothing I ever do is right anyway, and she says she does nothing wrong, it's all me. I'm at my wits end. Called her doctor today and left a message for Elder Services to talk to a counselor. And I'm made at my self feeling guilty and like I'm doing something wrong to find some peace and care for myself.
You have absolutely no reason to feel guilty. A person who is taken in by someone else typically feels happy and thankful that someone loves and cares for them. And thanks that person for their trouble and offers to help out any way they can.
The fact that your mother does not or cannot do these simple things is an indication of either dementia, a personality disorder or another mental illness. This is someone who needs three shifts of professional caregiving, not an amateur, as well intentioned as you may be. You need to keep you and her safe. It is not your job to make her happy.
Pam and Babalou are right. You need to see to it that your mother gets good care -- somewhere else.
But to answer your question, why do you feel guilty? Two part answer -- 1) Your mother installed all those guilt buttons many years ago and she knows how to press them; 2) our culture has a "can do, fix-it" bias. When we find ourselves in situations that we can't fix, we feel like it must be our fault.
You may not be able to totally disable the guilt buttons, but move forward in spite of the unearned guilt feelings.
Move Mother out.
If elder services isn't helpful, you can start the eviction process, which can take months, but you can at least start. No one should live in the sort of hostile atmosphere she is creating in your home.
I'm sorry if this sounds cold hearted, but she is clearly mentally ill and the stress of caring for her could well kill you. If you die, she'll be in a facility with no one to advocate for her.