<human>: Can you summarize the given text in a few sentences?

My dad has become extremely angry and irrational. While he can keep his usual calm demeanor most of the time he will get furious over simple, stupid things that never used to bother him. His family does has a history of Huntington's disease but he refuses to get tested for anything. His behavior seems to be in line with bipolar disorder which scares me. He constantly berates my mother to the point of tears over things that are not a big deal. He is impossible to reason with and he seems to live in his own fantasy world in which he is the victim and everyone hates him. My mother and I have tried to talk to him about it but he will not have it. My father never swears but recently has told my mom, me, and my siblings to "fuck off" whenever we try and help him with anything, and then scream at us for suggesting that he needs help. I am the oldest and the rest of my siblings live at home and are scared to death of him. While he hasn't escalated beyond verbal abuse, I fear that in time it might get there. Is there anything I can do? Sometimes I feel like calling the police but I am not sure they can do anything unless a crime is committed.
<bot>: My dad has mental illness and he refuses to acknowledge it or get help. I am scared for my mom and family.