I'm frustrated with my paranoid and pessimistic grandfather
What is making you so frustrated?
I'm tired of his paranoia and pessimism, I think they're disgusting
It sounds like he might not be in the best health. I think that you should try to let it slide a little bit since he is in such bad shape.
I feel bad for him, but it is my family and not yours. You are being too compassionate for your own good.
Even if you are frustrated, you should still have a compassion for your grandfather. You should see if you can help him in some way.