Early Alzheimers: He thinks he can do things he no longer can

First, I want to say how much I appreciate this group. It is always a comfort to read the stories here. It makes me feel not so alone. My husband has been diagnosed with MCI due to Alzheimers. His abilities are starting to decline and he has almost no immediate memory. He will ask me over and over the same things 3 or 4 times in 15 minutes. He is still driving and doing okay with that locally, although he does sometimes get lost now even going to familiar places. My biggest problem is he still thinks he can do everything he has always done. He does not realize how confused he gets. He could not really live alone anymore. How do you help a person understand that they need help. He wants to take a trip to meet someone to fish and the drive would be 3 hours. I am still working and unable to go. When I told him I did not think it was a good idea he got very angry and suggested I stop telling him what to do. Then he said I could just leave. The other day he wanted to fix the electrical part of the garage door opener and since it was dealing with electricity, I told him I thought we should get an electrician to do it. This is something he could have formerly done. He asked me if I thought he was an idiot and blew up about that. I can answer questions all day and listen to the same stories over and over, but I do not know how to handle his anger and keeping him safe. I would appreciate any suggestions.