You don't have to have anything to do with her if you don't want to. Just make sure you won't have any regrets once she is gone, which really could be any day at her age.

You could also choose to have very limited contact with her, and you can set the boundaries.

Yes. I went LC and NC with a narcissistic family member. Would still be NC or remained NC if she didn't start dying and needing help. humph
And the "being nice" thing was a manipulation ploy towards me to get what she wanted, be it money, information about other family members or to learn about things in my life she could weaponize later in an argument. I didn't regret my choice when she died. What I grieved over was that potential lost relationship that could never be.

There is a scene in a show called Bojack Horseman that demonstrates what I felt and puts it beautifully in to words.

Here's a quote: "Suddenly you realize you'll never have the good relationship you wanted, and as long as they were alive even though you'd never admit it, part of you, the STUPIDEST goddam part of you, was still holding on to that chance. And you didn't even realize it until that chance went away."

I haven't had contact with my father since 1995. And other family members for a bit less time. The whole "they're family" argument is complete bullshit. If they're toxic, cut them off, or as others have suggested, restrict it if you have to be around those family members. At most, be civil, but don't engage.

Unless you live with her or see her very regularly, it seems like you ought to be able to maintain some composure and politeness, but nothing more.

I'd cut ties.

Your entire family is made of people, and a certain % of people are just not worth having relationships with and the more you try the worse they treat you. Unfortunatly your family seems to have one of those people within it. Not your fault.

You run into enough destructive people just living your life, no reason to think just because one is a relative you need to have a relationship with them.

All relationships need to be two-sided. You should be getting as much love and comfort as you are giving. At 84, your grandmother is not likely to change her behavior and it does not seem like being too close to her is good for your mental health. I have learned that when I have had difficult family relationships, I need to keep that person/relationship at arms length.... I only interact on a level that I can control and tolerate (small doses). You need to keep yourself safe from mental abuse.....and there is nothing wrong with that.

At some point you need to accept that people won't change. Leave the door open, but stop trying to make them come it.

I have this relation with my father. I have nothing against, but I simply stopped trying.
Whenever I go to my home town I go to visit my aunt that works for him, and give him a hello. and that is it. If he wants to get close or to talk I am there, he knows, but I won't try anymore.

My mother is the opposite, If I allow her to do what she wants, she will merge her life with mine and start taking decisions on my life regardless my opinion, so I need to shield the things a little bit from her

That is family, protect yourself from harm and leave the door open for them if you can, but don't waste mental health trying to get close to people that don't want.

Oh fuck that. We are under no obligation to maintain a relationship with toxic people, no matter how close the bonds of blood.

I came to that conclusion years ago when I got sick of basically begging my mother to love me. I’ve simply cut her out of my life and have zero remorse about it. I’ve thought long and hard about this, and I have zero fear that I’ll regret my choice when she dies. Why should I? She was a terrible mother when alive; why suddenly deserve my sympathy and guilt when she’s dead? (And I’m not normally a heartless person by any means ... just goes to show how awful she is.)