My father in-law Alzheimer's disease is rapidly progressing. He is showing aggressive behavior and can become violent. What do we do?

His Alzheimers disease has greatly progressed down hill this last year. His wife, when he does something wrong or different, she scolds him. which inturn causes him to be aggressive and violent. 911 has been called twice now. His wife does not have the compassion to care for one with this disease. He is a retired Veteran. My wife and I know that his condition is only going to get worse. We are trying to get the VA to declare him 100% disabled so that he can receive care from the VA. My wife and I just dont know where to start. They are on a very fixed income, which all the healthcare home we have looked at, there is no way they can afford it. We just dont know what to do or where to start with the VA in getting him declared 100% disabled. He cannot leave the house at all by himself, he cannot remember anything from 2 hours ago. He truly needs 24/7 watching.