If it is any comfort, I certainly know how you felt. My grandmother came to live with us when I was 16 and stayed a year before my father was forced to put her in care. She was undiagnosed with Alzheimer's/Dementia (it wasn't a thing back in 1986) and it was my sister's job and my job to take care of her when we got home from school (before my parents got home). My wife cared for her ex-husband's mother during her final years with dementia and both me and my wife cared for my wife's mother during her final years of Alzheimer's. So, both my wife and I have been through this twice over (and my sister at least once). My condolences as well.