I'm very sorry to hear about how dire your situation is. It does sound like things may have deteriorated beyond repair. I hope not, but the worst may well be true. Do ou have some place that you could go for a few days to see if it helps to cool things down a bit? Ending such a long term relationship so definitively seems like a last resort surrender. Maybe if you guys were apart for a few days or even a week or so that might allow him to get some better perspective on what you mean to him. Also, have you talked with his nephrologist about a possible change to his medications? I still think that one of his meds may be the culprit and there are lots of alternatives to almost any of the immune suppression plans that are commonly used. Is he taking steroids? Those are notoriously bad for "'roid rage" and can be replaced by other meds.
As for my own situation, once I figured out what was going on, it has been pretty simple to catch myself when I start to feel something like that coming on. Actually it only happened a couple of times before I realized what was happeneing and they were very isolated incidents so over all our relationship was always on firm footing. Your problems seem to be almost a constant situation which is much worse than what we ever had. We are both still very much commited to fighting through this together through the good times and the bad times. Your husband does seem to have lost all perspective and self awareness.