Hi , I am beside myself I know my father is mentally ill because he has the same symptoms as myself but he has never had a eval. He was very abusive to his family when we were younger and now no one except for myself wants to help him. But where to I start how do I get him to get help thanks Please Help

Firstly, why don't you take him to see a professional who might come up with the correct diagnosis?

He is set in his ways and I am afraid of him ,afraid he might go off on me I am not sure how to approach him

At some point in time, when parents get very elderly we have to "make" them see doctors or take them for help.

Sit him down and explain to him in all seriousness that you think he needs a doctor and not for mental illness but for physical condition. That way he might agree to go and you will then take him to psychiatrist.

At 81 is it possible he has begun to suffer from dementia or Alzheimer's? You state above that you are "afraid of him" and "he might go off." These are VERY common symptoms with the 2 disorders I mentioned. A full health screening by a medical professional, just a regular doctor who you have spoken with previously about your concerns, may be the path you need to start on.