I don't think anyone should feel guilty about anything they ever think in these situations - even if those thoughts are that your family member might be better off if they were no longer alive.
It's good that your brother checks himself into the hospital when he's suicidal. That means he has some level of insight. The thought that you're something special, even after the voices are gone, is common - so is the drug abuse I hate to tell him, but my son's been Jesus too, and God, and the Devil, and Biggie Smalls - he's a smallish white guy, so that ones kind of funny.
My son would probably have tried heroin too if he had a way to get it. Instead, he got a nasty opiod addiction - same as heroin, but it's a prescription. He said it made everything right with the world too - and I could see that it did. Not that it's a viable solution.
Has your brother been compliant on his prescribed meds? or is he now? do they work?
Other than the drug abuse, what's gotten bad enough that you want to disconnect from him now?
If that's what you want to do, that's fine - no one would judge you.
But, if it's not really what you want to do, maybe learning how to handle your own emotions about the situation a little better could help you stay in his life.
There are therapists out there that specialize in helping caregivers - if I ever get a quiet moment in my life, I plan to go see one. In the meantime, I try to keep my sense of humor & when things get really bad, I just wait for the opportunity to get my son to agree to go to the hospital to get help. And, I vent on here about all kinds of things.
Maybe take some time away from your brother to get some perspective & then make up your mind about how much you can handle without sacrificing your own life?