My Mom is 89. I live with my Mom. She has suddenly developed this behavior. I have been doing 24/7 for many years, but now I am just needing some support and to at least know someone knows how I feel. I want to help her but she won't let me. What I feel is her pushing me away...how do I do it all?
Whether this is Not Her Fault (because of dementia) or it is Deliberate Manipulation may change how you feel about it and toward her. But it does not change the solution. You need and deserve to protect yourself. You have successfully been her caregiver for many years. Good for you!
The current situation is apparently beyond you to cope with. Not Your Fault! You need to bring in sufficient help to reduce the stress on you, or to figure out other arrangements. Is Mother living in your house, or you in hers? That can make some different in the options open to you.
Has Mother been paying you for her care? Do you have some savings, etc.?