We are having this situation with my DGM who has become intransigent, stubborn and sometimes manipulative and mean in order to have things arranged as she likes and maintain an illusion of independence. I'm quite involved in her care as my DF has poor health and no living siblings, I'm the eldest DGC and the others either live abroad or have additional needs themselves.
How she has behaved in recent years and the impact it's had on DF and his wife, and now me, has changed how I see her, that's inevitable. Unfortunately, old age can bring out people's worst traits when they are struggling to come to terms with losing their independence, their bodies and/or minds failing them, their world shrinking, living with chronic pain and discomfort, facing the end of their lives. It is important to have empathy and understanding for the pain and fear that drives the behaviour, but it also is important to acknowledge what that brings up for families, especially those who become carers. DGM sometimes can be selfish, unreasonable and devoid of empathy for us while we are expected to have an endless well of it for her. I want to do the right thing by her, I do have compassion, but I'm no saint, it does exasperate me at times.
I've learned that lots of conflicting emotions sometimes need to sit uneasily together. It is inevitable that they may at times feel frustrated or even resentful at the burden it's placing on you. They may be sad that they are losing the DGF they knew, as well as angry at the unfair expectations he is placing on you and DH, or even guilty that they get to live their lives freely while you are run ragged. Don't try and force empathy and shame any negative feelings, because making space for all feelings is how we move towards acceptance, and if we can accept our own less noble feelings, we are also more able to accept them in others and move towards compassion.