I sold his car two years ago and everyday he asks when is he getting his car back. I believe he cannot drive safely. Doctor has told him the same. He blames me and doctor for not driving. Screams and yells and asks day and night about getting him a car. I can't stand it anymore. My health is starting to fail with the stress.
For my husband, losing his license was the absolutely worst part of having dementia. He mourned for his special edition Miata for more than a year. The inability to drive is a huge loss for anyone. Your poor husband! (And mine, too.) Obviously we can't let our loved ones endanger others, But we can be sympathetic about their loss. Have you tried agreeing with him about how terrible this loss is, and how much you wish he were still able to drive, and how much you hate this dreadful disease that causes these problems?
A social worker suggested that my husband get a personal mobility cart (electric scooter). I thought she was nuts! But we got one and hubby was able to go to the library on his own, and to get his haircut, and to buy an ice cream cone. Depending on where a person is with the dementia, giving them a scooter may or may not be feasible, but it does provide a level of independence. It doesn't make up for not driving, but it helps.
This is sort of like dejavuagain's experience. Hubby asked his doctor if she would let him drive if he passed a driver's test. We have a rehab service that serves persons with handicaps and performs driving tests, to determine what car modifications, if any, would help someone be able to drive and also whether someone has reflexes and cognitive abilities to make safe driving possible. The doctor said, "Yes. If you pass the tests at Courage Center, I will write a letter to the DMV on your behalf." This was a pretty safe promise, because he clearly would not pass the tests. He never insisted on taking them -- deep down he knew he could not drive.
You need some relief from this constant badgering. Have you discussed it with your husband's doctor? If there is anything that can be done medically to calm him down a bit, that would be worth trying. I don't think there is a way to make him not care about driving, but I hope there is a way to help him not take it out on you.
One brother contacted the DMV in Florida (which has a LOT of flaky old drivers on the loose!) and they told him that if a doctor or family member (and I'm sure a police officer) deems a driver unsafe they can submit a form attesting to same. The individual will then be called in for a driving test. Well, that's all Mom had to hear. She was insisting all along that her driving ability was as good as ever, but the minute she was faced with having to take both a written and a driving test, she demurred. End of story, and honestly I think she is enjoying being chauffeured around without having to think about traffic.
In your case, this ploy may not work if your husband is to the point where even failing a driving test would not convince him that he shouldn't drive. Then he can blame you, the doctor AND the DMV! Best of luck with this situation.