Wow, that sounds extremely stressful for you.
By "tirades"- do you mean rages? In particular, rages in which your brother get "stuck" or obsessed with a specific subject and rages on about it?
What happens when your sister, you, or both of you talk with your brother about your concerns...is he able to hear you at all, or is is wasted words?
From your description, my vote is with your brother having a mental illness.
And yes. This pandemic is nothing short of a horror show. As the time winds on more and more individuals and families are becoming increasingly stressed. For some reason, for the first time today the whole thing has me scared.
__________________
|