Elderly spousal abuse?

For the past five years I have worked for an elderly couple as a housekeeper. The wife is disabled and the husband has late stage Alzheimer's. About six months ago I started seeing changes in his normal routine. The first time I knew something was wrong was when I arrived he was still in bed late in the afternoon. Then after he had lunch he slumped over in his chair and fell asleep and was unresponsive to what was going on around him. That same day his wife admitted to me she had given him some of her meds the night before to calm him down after he woke her up believing someone had hit him in the back with a board. She believed he had fallen again. When I asked her if she had taken him to the doctor she said no. She has since had hip replacement surgery and now has a personal aid come to stay with her in the afternoon and two nurses come daily to check on her. When I arrived last time to clean, my clients husband was still in bed sitting on the edge of the bed doubled over with a pillow in his lap as if he was in pain. He was wearing a t shirt and no diaper. He is incontinent and normally always wears a diaper. His bathroom was covered in feces as has been the case for the last 4 months every time I would arrive to clean. His wife was upstairs laughing and socializing with her aid and nurses while he sat downstairs alone in his room. I alerted her nurses and her aid about his condition. They all said they were only there for her care but they did go talk to him to see if he was alright. I had a long talk with them in another room after they checked on him about how his wife had been leaving him alone prior to her surgery with no phone and no emergency call button and to the fact that she kept saying she would get him help but never did and to the fact that she has POA and to the fact that the money they have is his since her constant excuse for not doing anything to get him help was no money. He needs assistance with all of his personal care. That same day her aid told me that my client admitted to her she had given him some of her valium. The aid said one of the nurses were told and just shrugged and seemed indifferent. My clients husband does not wait on himself does not prepare his own food and does not take his medication until she gives it to him. I have found several of his pills on the floor around where he sits. Although I have seen him on a few occasions before his Alzheimer's became so advanced, have a surly and sarcastic personality so did she. I have seen her talk bad about and mock people on several occasions. She has said that she believes his bad behavior now is intentional and spiteful at least half of the time. I think he's beyond that capability at this point. His daughters live out of state and they do not ever visit him so that does indicate he may have been an awful parent. So I don't know what more I can or should do or how much farther I should get involved in this. I have thought about contacting APS but I know even if I do it anonymously my client will figure it out that it was me and I will lose her as a client. I know I cant continue to watch the man slowly dying with no one around him that cares. He is definitely not dying with dignity. I have no idea how bad of a person he may or may not have been when he was younger I just know that regardless it just seems wrong the way he is being neglected and ignored. what are your suggestions?