I love my grandma so much but I go to her each year for 1 month she is really good to me but I don't want to talk to her as she is toxic.I am someone who struggles with feeling worthy and believing that I am good enough to be loved etc (self-esteem struggles).She manages each time to convince me that my step-father doesn't love me and that he doesn't see my as his own which he claims he does.Which then gives me have a hard time as I struggle internally with my thoughts and then am burned out emotionally as I believe her and what she says of course isn't true.I love her but I can't go through another emotional burn out.I will maybe stick with small talk such as hello how was your day I love you etc.
Currently going through the same with my own gran at the moment. I love her with all my heart but she brings me down and I've had to take a step back from her for a bit for my own health and happiness. She wont support my wedding, she criticises what I look like, what I choose to do with my life, always casts up that I don't want kids and has said some nasty things regarding my health. I'm her only grandchild so she has super high expectations of me.
I know how stressful and hurtful a situation like this can be and you're right, it does burn you out. I think its essential to take some time out from toxic people, even if they are family, for your own wellbeing. Sometimes a few days of a break is enough and sometimes it has to be longer but you'll know what is best. I hope one day you are able to sit down and talk to your gran though and hopefully work things out.