I'm so sorry you are not getting the support you need. It is a sad fact that parents have as hard a time being parents as they have being people but they are individuals and it sounds like your mother has a lot on her plate with her husband/your father and your brother making it hard for her too. Does she work/have money? Has she "made something of herself"? It does not sound like it so what you are trying to do may be foreign to her and she may be as "trapped" as you feel at the moment. If she has no other way to make a life, she is stuck with your father/brother and their antics?

Do you have any good friends from school or before who could help you? I would stay away from your brother and father as best you can, get your operation and out of your parents house and truly move on as soon as you are able.