Any advice for dealing with a narcissistic Mother (89) who is often very mean and has always had ever-changing moods/personalities?

My mother can be kind, cook for me, and be pleasant but I am always, always "walking on eggshells." She can be so mean, accusatory, jealous, demanding, sarcastic, belittling, spoiled/childlike, but when things are "going her way," at times happy and content. This has been through my entire life -- I am now 63. I am seeing a counselor and this has been helping, but I am hoping some of you can share your stories and ideas. She becomes mean and rejecting when I do something with other members of my family, even though she has been invited, but chooses not to go. She has ruined more holidays than I can count because something didn't go her way. When I go out of town, it is a major production, even if it is just for a two or three night mini-vacation with my husband. I rarely see my children who live in other states because she gets so depressed, upset, etc. over any separation from me. I am an only child and have felt the oppressive weight of her moods and never-know-what's- coming-next demands for my whole life. My father was a loving man, very sweet, but sort of gave in or turned her over to me. My father died 15 years ago and my mother promptly moved near me into a duplex about a mile away. Since that time, I have felt somewhat like a prisoner because I cannot relax and enjoy my life without her constant calling, complaining, etc. I have recently set limits, and I am so much better than before, but it is still so stressful. I am truly so nice to her-- do multiple things for her on an almost daily basis, take her shopping, have lunch with her, clean her house, take her to the doctor, whatever. I realize many of these things are age-related and I accept this and am happy to help. But when she is so mean and rejecting--well, that still gets to me, even though I am slowly improving. Lastly, I want to share a dog saga--my mother has always had dogs. She relates better to animals than people, BUT, like me, the dog has to "behave perfectly" in order to get her kindness and love. SO... She has been bemoaning her loss of her dog who died six months ago and she has tried out four new dogs, and they have all been returned because they peed or pooped in the house, or seemed to be sick in some way. I have been the one to return these sweet dogs to the shelter and it makes me ill. I feel horrible for the animals. The last dog was so sweet but she ate grass and threw up, plus pooped in the house, so there I went, running over to her place to clean up the mess, and the next day driving over two hours to return the sweetest dog in the world. I considered keeping this little dog but my husband and I am just now trying to figure out retirement and hoping for little bits of freedom and do not want a pet now. Lastly, for some background information, my mother had some traumas in her life, but was raised by a loving father and step-mother. I feel for her, and she continually reminds me that her real mother left her when she was two. I listen kindly and as patiently as I can. I feel for her. I am not a saint, but I have been told I am a nice person who has a kind heart, but I can hardly bare this anymore! She is in my head all the time and I am always waiting for the other shoe to drop.

So, like I said, I am getting better, but setting boundaries and sticking to them is the hardest thing I are ever done. My mother is "addicted" to me or something, and being an only child, I have no backup. She has no friends anymore --the few she had have died-- and she has alienated many people throughout her life. I cannot just leave her to her own devices, and she does not want to move into an independent living facility yet. I am not acting to make this sound like a "poor-me" pity party, but that is kind of what this is. Please help by sharing stories, struggles, or advice that has worked for you.