What was the outcome of "Shutter Island" regarding whether or not he was sane?

It’s really hard to explain and the movie was a little confusing. I know he created Edward so he wouldn’t have to live with what his wife to his kids and because he killed his wife. I think he was insane because he was seeing people and the other person he created. You know at the end when they told him the truth about his family and how he created this person and how all the names matched? They were trying to see if he could be normal again. He realized they were telling the truth and he remember everything and he told them what he did to his wife and all that. And you know his partner was really his doctor? But in the end he couldn’t be himself again because he went back to thinking he was a marshal on a case. Remember when they were sitting on the steps at the end. After he was told the truth and realized it all. I don’t remember his exact words but he was like we are smarter than them. We will find the truth. lol something like that. and his “partner” really his doctor was like yeah boss and he looked at that bald dude and shook his head because he went back to edward to protect himself and they couldn’t help him. He was still blocking the truth. lol i hope you understand what i’m saying.