It sounds like you have major family difficulties and your sister is not helping. But it also sounds like you are doing the best you can for you and yours and I would stick with that. Do not take on so much of the "blame" for the problems with your sister! Your uncle confirmed that she was off base; stick with what you are doing, you are doing well. I would not bother trying to discuss anything with your sister, it does not sound like she is trying to understand but to just get her way even if it makes everyone else miserable.