My dad is making our family miserable. this is LONG, sorry.?

Oh my goodness, you sound as if you are all in a horrible, horrible situation. I think you need to sit down with your Mom and have a good, long talk to her about your feelings, your worries and offer to be there for her to help her and listen to her if she needs to talk about things. It sounds as if your mum could do with some help in the form of counselling (and I say your mum rather than dad because it sounds as if your dad is somewhat of a lost cause, and doesn't care about resolving anything, whereas your mum does). It is very, very sad because it sounds as if your mum is doing to lose out more than anyone else from this, especially with her health. Ideally though both your mum and dad should get counselling, either from a health professional, or even perhaps a priest as experts in family counselling and help.