My relationship with my father, now dead, was similar to yours, and he had Alzheimers also, which made his rantings even worse.
The one thing I can tell you is that he will continue to "tear you down" until his mental capacity deteriorates to a point where he can no longer put an understandable sentence together. Then he may turn to violence. What finally prompted me to put my Father in a Nursing Home is when, while trying to get him in bed, he kicked me in the stomach so hard that I flew across the room and hit the wall, and I wasn't a small guy at the time.
Oh, and the "mental beatings"? They will go on long after your Father is dead. Whenever I'm having a difficult time with something, I can still hear my Father calling me a "Worthless POS", or saying "You are the only thing I really failed at". I try and use that in a positive way, sometimes it works, others, it doesn't.
All I can do is offer my understanding, as much as it sounds bad, things got a bit better for me once my Father died, maybe it will be the same for you.