@HunterJamieson hello I can relate to this situation as my brother has schizoaffective disorder.
I have found around 'these people' you often have to demonstate, like being a teacher or something "that you are absolutely perfect and need to behave in a way to avoid triggering their constant anxiety and delusions". Its exhausting and impossible. They don't trust their own senses and reality, they dont trust things and people within that reality so you can easily get stuck in a game where you are editing your life constantly to avoid an outburst from the person who does not share the same reality.
Then there's enablers around, an example from my life my mother walks on eggshells around my brother and indulges all his delusions so that her little baby doesn't throw a tantrum.
Myself I just wanted a peaceful life that didn't contain daily arguments, tantrums, meltdowns, accusations, domestic violence I turned away from that family to find myself a better life. Note I wanted a BETTER life, I got a better life but not an EASIER life. If I had bought into the situation I would be getting family money and having an easier life. But, the cost of an easier life was too much suspension of disbelief for me and I am happy to talk to my brother on the phone and dispel his delusions, I am not happy to be expected to believe them for my mother's benefit of "my kids are crazy and I need to be intoxicated to deal with it". That's a story I want to leave behind with the family members.
So I wish you well if you have found the line between "your problems" and "your brother's problems" then you can hold onto your own reality and build a positive and contented life from there.