Options for abusive aggressive Grandmother?

Thank you for reading this question and hearing my story. I apologize in advance for its length but I am in search for some options on how to handle a situation dealing with my verbally/emotionally abusive and aggressive grandmother.

Some backstory, several years ago when I was single I moved into a house my grandmother previously owned that she asked my parents to take over because she could not maintain or afford it on her own. My parents were losing money trying to honor her wish to die in this home so I decided to move in to help my parents by paying rent. I also wanted to help my grandmother since she lived alone when had shoulder replacement surgery due to a fall. My good intentions quickly were discarded and my eyes opened when she turned overnight from my loving grandmother to someone i didn't even recognize. She would yell, scream, throw things around the house, threaten me, and use any information she got against me when she was upset with me for doing things like "touching her stuff" when i cleaned the home. Everything was her stuff and because she couldn't clean i had to start doing that when she wasn't home. She is OBSESSED with this house but its not her home anymore. My parents have dumped thousands and thousands of dollars into this house to fix it up since my grandmother let it deteriorate so the state wouldn't take it and my husband and i have also invested a lot into this house since we got married last year (i.e. painting, fixing up electrical, new appliances, furniture, etc.) It actually looks nice for the first time in years but she would rather it fall apart. We love this house the community we are in but the situation with my grandmother is threatening it all.

My mother has MS and my father has his own medical issues as well with PTSD and physical disabilities from serving in Iraq. The stress of my grandmother has caused them both to become sicker so they limit interactions as much as possible for their own health. My husband and i have talked multiple times about moving out of this house but if we moved out not only would we be affected financially but so would my parents who receive NOTHING from my grandmother except complaints about us despite submitting paperwork to the state for her to have increased social security to pay something for rent or utilities. My grandmother has COPD, is on oxygen, is losing her vision, has high BP, hearing loss and has early stages of dementia but social services department of aging have said she is too high functioning to qualify for any services. I have tried finding a home care provider, setting her up with the senior center, but she refuses to go and says those people are old and she's not old (she is 86 years old).

In the past few weeks, she has been hospitalized twice for COPD related complications and a blood infection but is back in the house with a vengeance. We have caught her spitting on our stuff, taunting our dog like she will hit him, slamming doors, throwing stuff around the house, calling me names and threatening us. I do not know what to do except to move out. Her behavior has alienated all of my family from her and my cousin (who is her "caregiver") is not reliable. No one knows what to do in the family but because we are in the home we are left to survive on our own. My parents won't evict her because she has no money nor can we afford assisted living for her. I have called the cops in the past to report situations that became out of control when she was stealing our stuff but they just tell us to move out and they wouldn't do anything because of her age. She is very manipulative so we even installed cameras just for our own safety if she accused us of hurting her which she has done before. I am running out of options other than to cut my losses and move out. Is that really the only solution? I see it offered up a lot on these forums but what I would like to know if what others have done. Thanks!