Does anyone have a relative with Huntington's disease?

My mum has Huntington's Disease, a hereditary disease that affects personality by becoming fixated, aggressive, irrational and their body by choking on food, losing balances, twitches and eventually no control and not being able to speak. She has reached the stage where she is fixated on things like the weather and one of the aspects of the illness is the sufferer won't accept they have it and don't even notice the changes. My dad, sister and I have all tried to tell her she has it, but she does not believe us even after seeing two specialists. How has anyone else dealt with getting help? My dad has health problems, but he won't help me and has said he doesn't want to know, because there is no reasoning with my mum and he isn't bothered. My sister has 3 children and is a nurse, but she doesn't really want to know and I'm only in my 20s and dealing with this. I have my own problems after being affected at birth due to lack of oxygen and I just feel between a rock and a hard place. Should I talk to our doctor? It is so frustrating and hard to cope with and I feel isolated and am losing sleep over all the health worries.