Overwhelmed by decisions

Hello, all.I'm a newbie here. The "short" story: My mom is 79. She lives alone, about 20 min from my home. Her health issues are periodic bouts of debilitating arthritis, for which she refuses to take medication due to an overall aversion to meds with frightening warning labels,, as well as a sometimes racing heart. She's called 911 4 or 5 times over the past year and stayed in the hospital for a day or two while they ran various tests. Of equal concern to me is my mother's increasing forgetfulness. She also seems easily confused by things at times. (She is also hard of hearing but refuses to consider wearing a hearing aid.) Once I was talking to her on the phone and urged her to turn on a public radio station because i knew the music they were playing at the time was something she'd enjoy. She was unable to figure out how to use the tuner to reach that station. I helped her set up an air purifier recently to hopefully help with her dust allergies, but a few days later she returned it, saying it was too complicated to use. She couldn't figure out how to use the buttons. She did the same thing with a humidifier she bought. I can't talk to my mother about dementia or Alzheimer's. Her mother had dementia. She would probably deny that anything's wrong. My one sibling, an older sister who also lives nearby, has refused to contribute to care-giving for my mother, other than to talk to me. We've both had difficulties with the mother/daughter relationship over many years, but I have a lot of resentment toward my sister for leaving me with the caregiving burden. A good friend of mine keeps telling me I need to start making arrangements to sell my mother's condo and have her move in with me, but I often don't get along with my mother and while I feel tremendously guilty for being "the bad daughter," I am afraid having her move in here would be a disaster and we'd be fighting all the time. I want to find ways to help my mother without being swallowed up in the process and giving my life over to her care-giving. I am just now starting to research what resources are available and started reading an excellent book. Right now, she mostly could just use help with housework. She calls me daily because she is lonely and it often drives me nuts becus I have various other stressors in my life.. I am in my early 50s, single and have been either unemployed or underemployed since a job layoff in 2009. I am just scraping by now but unemployment benefits end soon and I'm working 20 hours a week making $12 an hour. I also get some work as a freelance writer and I charge $50/hr for that, but I don't have enough work to support myself, even though I paid off my mortgage last summer. I also have MS, which is mostly stable. While I would love to downsize from my high-maintenance home into a condo myself, I feel I can't move where I'd like to move becus it would put me further away from my mother. All feedback is welcome.