My heart goes out to you; Alzheimer's is a cruel disease (as are similar memory problems), causing not only confusion to those with it but placing enormous burdens on those who must take care of them.
Recently, I was talking with someone whose spouse has Alzheimer's and no longer recognizes her. Let me pass on some practical lessons she's learned. First, she said, find out as much as you can about the disease and what's likely to happen as it progresses. Second, it may be helpful for you to seek advice from a professional skilled in elder law, particularly if your financial resources are limited. In addition, don't get upset or angry if your spouse doesn't follow instructions; she probably can't understand them. Instead, always let her know you love her, no matter what happens. Finally, don't carry this burden alone, but seek help from others, even if it's only for a few hours a day.
Most of all, my acquaintance said, turn to God every day for the strength and wisdom you'll need in the months and years ahead. Remember: We are never alone when we know Christ. God's promise is true: "The Lord is a refuge for the oppressed, a stronghold in times of trouble" (Psalm 9:9).
Let me add one final point: Although I know it won't be easy, learn to thank God for the privilege of helping your loved one during her illness. Wouldn't she have done the same for you?