I have tried driving him around hoping he will forget about it but he just gets angry because I can't find this imagined house where he says his wife lives. He doesn't recognize me during these episodes and gets quite upset and fearful. If talking fails do I physically restrain him? If this happens in the evening and I can usually get him to bed, he forgets about it in the morning, but then it starts all over again. This happens several times a day.
If it's dementia, there are medications that may help, but I would make arrangements for the safety of you both. According to what you describe, he could hurt you not realizing who you are. I would consult his doctor and see if there is a facility where he could be admitted inpatient to have him diagnosed and/or treated to get his delusions under control. You won't last long without proper sleep.
I agree with Sunnygirl in having your husband evaluated. There are medications that can help his agitation. I know his agitation is a drain on you but it doesn't feel good to him either.
My reading on dementia and my experience taught me that this kind of behavior is quite common. Granted, there could be something else going on besides dementia, that's why I would get him properly evaluated. Then, you can know what you're dealing with.
My cousin progressed with her dementia from being a homebody to wanting to go to the mall or wanting to go in the parking lot to get into her car. Except she was in an Assisted Living facility, had no car there and was not able to drive a car. It was an unsafe situation. The mall she wanted to go to no longer existed. She would get very upset about not being able to get where she needed to go, but antidepressants really helped her. And this phase only lasted for a few months.
You never know how long a phase will last though. Just know that it could pass or it could last for years. I'd try to get some assistance in dealing with his needs. Even in a wheelchair, it's difficult to control people who are on a mission and are not thinking clearly.
You could also try "why, yes Jim, I'd be happy to take you; describe the street and that house for me?" "Was there a garden there? Describe it for me, what did you grow there? Didn't you have a workshop? ' yada yada....let him revisit those memories and describe what his mind is seeing. I've had to do that to my mom once when she didn't recognize me and wanted to visit my brother not comprehending where he moved.
Has your husband been diagnosed with dementia? How long ago? How old is he? How long has this delusion been going on.
Thinking that his "real" house is elsewhere and that you are not his "real" wife sounds very odd, but it is common enough to have a name. Look up Capgras syndrome and see if that seems to describe your situation.
Absolutely discuss this with his doctor.
I like sunflo's suggestion of agreeing to back him put putting it off for plausible reasons, like heavy traffic, or a water pipe broken in that neighborhood, etc.
If he says he will walk, try, "Oh, that sounds like a good idea. I'll go with you. We both need a little exercise." and then, maybe, "Let's just go down this street ... oh look, the malt shop is open! Can I buy you a chocolate soda?" In other words go along with him and also try to distract him. At some point you might say, "Oh! I'm getting a blister on my heel. I am so sorry! Let's go back now, and try this again tomorrow."
I don't think you are going to convince him there isn't such a house or that you are his wife, when he is in the middle of an episode. I'm just hoping you can delay matters long enough so that he sees you as cooperative even though you don't get him to the impossible destination.
If you get any good coping advice from his doctor, do share! We learn from each other.