Have to agree with what's been said. There was a time (which lasted several years) when I had actually forgotten what my husband was really like - his illness had crept up and changed him so gradually, into a paranoid, suspicious, controlling madman who made our lives a misery, and if I'm honest, the thoughts of him living on and on for years, in the perfect physical health (and at the time, we didn't realise he had dementia - like I said, it was so gradual, we thought he'd always been like that!) used to fill me with despair! I spent as little time as I could with him, because he watched every move I made with suspicious, glittery little eyes. And still wasn't satisfied. He was trying to police my thoughts, my beliefs - everything.
However - eventually his illness progressed. I now think that a lot of that previous time was caused by his knowing that "something" wasn't right, and desperately trying to (a) hide that fact, and (b) trying to maintain control, when he felt and knew that he wasn't in control anymore. Things were slipping away, and although he could hide it from everyone around him, he knew it himself. Later, I found files full of research he had been doing on alzheimer's disease, how to treat it, folk remedies to prevent it, herbal remedies, quack cures, etc. etc. Dating back years.
Further on, and as he progressed further into the illness, he lost all that control-freakiness. He lost the nastiness. It's as if, once he got to the stage where he no longer knew he was ill, no longer realised that he had to try and keep up a front of nothing being wrong - he was able to relax, and the real person shone through again. He became again the lovely, gentle, caring man he really was. And of course, medication thankfully dealt with the paranoia & hallucinations. So the last few years were really good - until he progressed again to where I couldn't care for him alone any longer.
Our minds are such a labyrinth, there's so much in there, any illness that affects our minds is bound to be difficult. But your wife is still in there somewhere. I'm sure there will be flashes now and then.