What can I do when I'm nervous about leaving my grandma alone?

I live with my grandmother, 86, and she has not been diagnosed with alzheimer's or dementia, but she has had 2 mental breakdowns (possibly from lack of sleep or medication?) in the past year, (and had to be hospitalized) so I am always paranoid that if I leave her alone she could fllip out again. She has very strong religious and political beliefs, and also watches news constantly, which can get her upset and want to write letters to the newspaper or contact someone. I have heard her opinions on these things all my life so I get very burned out hearing them all the time. I have bad anxiety and she has high blood pressure and we frequently get in arguments. I don't have friends or family who live close enough to help. I also have some driving fear so we are isolated at home most of the time. I only leave the house and drive to pick up groceries or go to doctor visits. I feel alone and stressed out all the time. Even when I do manage to leave the house for a short time, I can't enjoy myself, and feel like I need to hurry back home. My grandma insists that she is fine and I can leave her, but some days she gets depressed or upset over something she hears on tv or reads in the paper. She feels she needs to get her opinion out to others, and can get restless.
I also worry that she was given Seroquel at night to help her sleep, but she seems to have developed some strange mouth movements & noises during the day.
Any advice is appreciated, thanks