For your own health, at least take a proper break from her because ghus could go on for years. If neighbour is looking in on her regularly, you don't have to worry about that side of things. Seems like she has a few people running around after her! You and your brother have done your very best, but she is abusing and damaging you both. If she does die, you will have nothing to reproach yourself for. Keep contact with your brother. At least you have each other. I know how you must feel from the guilt point of view, because we only have one mum, but unless she becomes a bit kinder, your mental health will continue to suffer. Manipulation and control is going on here.
Tales about "stingy" guests and hosts.