I am so sorry to hear what you are going through. My husband is 95 & I am 86. He has dementia and like you we have always been inseparable. See if there is a senior center who might give some advice, or county health services. Caregiving a love one is difficult. My husband wakes me up in the middle of the night looking for me. At times he doesn’t even know who I am and later he does. Her actions to you could be she doesn’t know who you are. Hide the keys to the car. You might have to lie for her own safety. Tell her she lost her set. My husband was careless with his wallet. I removed all important cards so when he finally lost it I wasn’t concerned.
When he fell, I was told for them to get on all fours, knees and hands then placing foot on floor .from there assist helping for them to stand erect. I help at the last stage by pulling on his belt. You feel alone but remember the good times. Re tell some of the trips or things that brought both of you enjoyment. Try and get out of the house. Go for a drive (you driving) pick up an order of food or just around town, to a park or walk the mall. Best of luck on this journey of care giving.