Leanna... it is obvious that no matter the age he is not able to live alone or drive. No he does not understand this. He doesn't know what is wrong with him. It is up to you to make sure he is safe. That means no living alone and no driving.
First, do NOT let the truck come back to where he can see it. Leave it in the shop!! Or at least let him think it is still there. Telling him he can't drive with the truck sitting there is useless and only annoys you both. If it is already back then tell him it needed to go back for more repairs and don't let it appear again. Tell him because of the accident he has to stay with you. End of story. The more you try to explain and convince him that he is unable to live along and drive the more frustrated you are both going to be.
He is ok for the most part!?!?! He doesn't take his medications. He only eats junk food and not what is available. He drove to church on the wrong day, the wrong way, on the wrong side of the road, forced people off the road and hit a tree.... sounds less than OK to me. This can and will happen again, or something worse. Just the fact that he is irrationally obsessing about living along and driving tells you that he can not live along and drive. How young is too young? Early onset Alzheimer's Disease affects those in there 40's and 50's. There is no too young for this disease. You have to respond to his symptoms and not his age. What he has was a stroke. This causes further brain damage to add to the Alzheimer's.
If he is too anxious then ask his doctor for medication that might help him relax. Please do not argue with him or try to have a rational conversation with him to explain the situation. Give him a fiblet that validates is emotions and hope for the future (though you know it is not going to happen). "I know you don't like being here and not driving!" That will validate that you understand how he is feeling. "The doctor said you need to stay here a while and the truck is still being repaired, we will see what the doctor says next week."... big smile. You know he is not going home and will not drive again but this will give him something to hang on to for a while. Just keep moving the date up a week
Yes, he is going to repeat himself and not understand. You will have to be patient with him. His life has just changed in a dramatic way. He has lost his independence and mobility. He does not understand why these things have happened to him. He is scared and frustrated.... far more than you are. His damaged brain will not let him understand. He thinks he is fine and the world has just gone crazy around him. Please be patient with him!!
Yes, you do need to find a support group. You have found one here and we will help in any way we can. You can also look on the Alzheimer's Association web site for support groups in your area. They can be a great help and you can contact with those locally that are going through the same thing. If you have a particularly difficult time, rather than getting angry at him, call the Alzheimer's Association hot line. It is manned 24/7 with amazingly knowledgeable individuals that can help you. And you can put your questions, frustrations, and venting here any times.