One of the difficulties is that if you are in a co dependent relationship, and have been for years, and you are someone who identifies themselves as being the loving, caring, sympathetic one, then it is going to be extremely difficult to go straight to hating your partner.
So I expect that for a while you will keep trying to forgive him or make excuses for his horrendous behaviour. That's Ok as long as you keep working on getting out. You can realise what a total shit he is and all the good times that he has stopped you from having in due course. What you must keep in your head is that this relationship cannot continue. It is not your fault in the slightest, but so what if it were? Do you think that anyone should stay in a relationship which they have tried, unsuccessfully, to make work for 15 years?
For now maybe you should just concentrate on the fact that you can't live like this and that you need to move on. The anger can and will come later.
Fwiw this illness seems awfully convenient. I agree that if he is so ill that he needs round the clock care then he should be in hospital. Even if he is ill it sounds like he is using it as an excuse to get you running around.
On a slightly different note, I expect that a lot of what you think may be 'your fault' is nothing much and certainly not worth any amount of self flagellation.
My ex used to get so angry with me for being absent minded, which I am. It took me ages to realise that forgetting your keys now and again is not the crime of the century. One day DH said to me, after I practically threw myself down on the ground to beg forgiveness,
'you know I really don't care if you are in a bit of daydream from time to time. In fact it is quite endearing. I love you for x,y and z, not whether or not you remember to pick up some milk, so can you just stop apologising etc etc.
Just saying
Stay strong and talk to rl people when you can. It will take some guts but it's such a crucial next step
Good luck and thanks for posting again. I keep thinking and worrying about you!