Ok so your mother is a controlling narcissist who has ruined your relationship with your siblings. Might have been better to put that in the first post.
I alter my advice from my previous post.
I still wouldn't go see him, even if the only reason he's saying that is because he's under her control, you have to remember that he chose to remain married to her despite being able to see what she was doing to their children, you and your siblings. It wasn't to protect you, he chose to remain after you'd all grown and left. He also could have protected you better by giving you a non-toxic home 50% of the time if they'd split. So he chose this situation - if he's under her control, it's where he wants to be.
Don't worry about whether he really means it when he says he doesn't want to see you or if he understands he won't get better. He's either saying it because he wants to or he's saying it because she wants him to. Either way, he chose this situation, this marriage, so it amounts to the same thing. Stop wasting your energy trying to work them out and just take whatever they say at face value. There are some plusses as others have said, you won't have horrific memories of his last days/weeks/months.
But I wouldn't support your mother at all. I'd go NC as soon as the funeral is over. Sounds like you're pretty much NC with your siblings too. It sucks to have no family, but being part of one that's causing you so much ongoing pain is completely pointless.
I doubt any of these people would be there for you if you needed them. So give over your energies to yourself and your recovery from grief, instead of giving them to other people. You'll be called selfish, but unless you run around doing your mother's bidding 100% of the time until the day she dies, you'll be slated as awful anyway, so it doesn't matter. (I'm sure she'll revel in the attention of being the grieving widow, having everyone rally round and will play the part to the fullness of her capacity. She won't cease her triangulation or be grateful for your help). Families like this are a hellhole, so cut yourself loose and live the rest of your life in whatever peace you can find.
Don't worry what "the village" think. Even if you live in a literal village where everyone knows everyone's business it'll still soon blow over. People aren't thinking about us as much as we think they are anyway, it's one of those guilt buttons narcissistic parents installed in us, to worry more about others perception of us than what is actually happening. You know you're not a bad daughter. It doesn't matter what others, who aren't in the loop as to your family dynamics, thinks.