You have lots of sympathy from me. My late OH needed lots of care and support due to Parkinsons which began when he was about 60. I took some decisions when things started to get bad - I resolved that I would make sure I still had a life and organised a carer to be with him so I could continue my musical life and go to rehearsals etc. I absolutely knew that without that I would go insane and my ability to care for him would dwindle. I kept this up right to the end, and indeed eventually he went to a nursing home as I could not longer cope.
He did behave strangely towards me because of his paranoia - he thought I was trying to kill him - but, as he was very physically disabled in the last year, I did not feel unsafe, although he did shake his grabber at me in a threatening way - I just took it away - not ideal, but what ese could I do? It was deeply unpleasant, but I knew I was physically safe.
I do not know the exact disabilities/health problems that are afflicting your OH, but there was a specialist nurse for OH's illness and she was my lifeline.... experienced, knowledgeable, responsive, and kind. I do not know what I would have done without her.
You have to reach out for help, even if that is not what your OH might choose. The bottom line is that you must get your head round the idea that YOU matter too. It is very easy when caring for someone who has been unlucky health wise to feel that you have suddenly stopped being important in any way and that your needs are an irrelevance. They are not - they are critical. I knew that I would not be able to help him if I did not also help myself and give myself a sporting chance of coping. There is nothing to be gained for either partner if the carer allows themselves to sink.
So - talk with the health professionals, social services, relevant voluntary agencies, citizens advice. Prioritise your own needs and go all out to get these met to the maximum possible. It is not selfish; it is realistic and sensible.
Some of the process of getting help involved some complex financial issues - benefits applications etc. - please get all the help you can with this. I dipped into our savings to make sure I could pay someone to be with OH while I got out of the house. It was worth every penny and kept the whole situation afloat.
Make sure you take care of yourself - you matter. The question "Who cares for the carers?" is an important one.