This isn't like my grandmother but I know she has no dementia and no Alzheimer's and if anything they said just denial. I don't understand but it's to a very bad point.... Where it's dangerous for me. I was never much of a quitter but she is being so cruel to me and my health I don't understand.
What doesn't your grandmother care about that you are hoping/expecting she should care about?
What are your grandmother's care needs?
What are your health issues?
I'm sorry to throw such a lot of questions at you, but without understanding what has happened we can't really suggest how you might be able to change anything.
If dementia has been assessed and is not being considered, at least for the time being, has she been checked for a UTI? Depression? Sensory changes that can lead to depression? There are many things that can cause changes in older people.
Maybe yu (?) have decided that she is being “cruel” a little too soon, because if she’s always loved you and treated you well, and you’ve always loved her, a sudden change in her attitude may be because of something else, unrelated to how she really feels.
If she’s seen by a medical doctor do you go with her to her appointments? Have you done a Google search on problems of 80 year olds? Geriatric diagnosis? You may find some helpful topics and suggestions there.
Good luck! Hope you FIND some answers that will be helpful to you both!