My heart goes out to you and your family...
Is your father undergoing any treatment whatsoever for his condition? It sounds like he needs to see a neurologist, perhaps a family doctor can refer him. Is your father AWARE of his outbursts, personality issues, etc? Can you possibly document (i.e. videotape) these episodes and show them to him?
My ex-husband was diagnosed with delusional disorder Type II (reality-based delusions), which makes it IMPOSSIBLE for him to trust anyone, including loved ones. Unfortunately, such conditions exist and make it difficult for the family,
Your mother needs to be protected from such stress in order to heal. Your father needs to receive medical treatment, possibly in-patient, as well as unconditional love and support. Don't forget yourself. You all need emotional support. I recommend you and your mother read the book : Love, Medicine, and Miracles by Bernie Seigel.
Please don't hesitate to contact me if you need someone to talk to.
God Bless,
~Leslie