Mom (86) abusing Dad (91).

My mother is, and always has been, verbally and emotionally abusive. She has been diagnosed with borderline personality disorder and narcissism and has been the cause of extreme distress all of my life leading to many years of counseling. Presently, mom is 86 yrs old and is in good physical condition, dad is 91 and suffers with heart disease, diabetes, dementia and alzheimer's. Mom and dad live in their own home and mom is, supposedly, dad's caregiver but, in reality, she is not fit to care for anyone and is abusing my father. Recently dad told me he would divorce her if it were at all possible at his age and with good reason. He is physically very fragile yet requires what I consider minimal care at this stage of his life. His basic needs consists of 3 meals a day, blood sugar monitoring and medication which is supposed to be administered morning, noon and night and that's the extent of it, however, way too much for a resentful, selfish old woman who says she doesn't have the personality to 'deal with' my father after 66 years of marriage. Dad has been a dedicated and faithful husband, an excellent provider and a loving father but, apparently, he no longer serves a purpose in her life and she has no problem stating that she wants him gone and thus lies the problem. I am all too aware that she neglects my father's needs and is verbally abusive. Sadly, Dad has been in crises several times over the last year and they have, each time, exposed neglect on my mother's part. She simply stops giving him his medication and doesn't attend to his basic needs as described above. My brother and I cannot bear to go to their house because we are afraid of what we'll find. Several months ago dad spent days on end asleep in his bed. This was an unusual development so I checked his meds and found that over 40 pain pills were missing. When I asked my mother, who administers his medications, what happened to them she said she didn't know and claimed that somebody stole them, accusing me at one point. Shortly thereafter I noticed my father was experiencing a diabetic induced stupor and it was, again, after checking his meds that I found out my mother had simply stopped giving him his diabetes medication because she couldn't be bothered to check his blood sugar 3x a day. Besides being stuporous, dad lost 10 pounds he couldn't afford to lose, lost his sense of taste and appetite, was extremely dehydrated, had trouble walking, fell down on numerous occasions and was experiencing pain and numbness. As you can imagine, my brother and I are not only sad but horrified, angry and at a loss as to what to do. Although we have tried to intervene on my dad's behalf we dare to confront my mother as we know we will be met with verbal abuse, temper tantrums and lies followed by acts of passive aggression aimed at my father, my brother and myself. I would like to walk away from both of them at this point as my nerves can't take much more but my conscious won't let me. My question therefore is this. How do I expose and circumvent my mother due to the fact that she, his caregiver, is abusing my father? She puts on a good act in front of the doctors and is agreeable to everything they say regarding my dad's care but does not follow through with their advice once she gets my dad home where no one can see what she is actually doing to, I believe, expedite his demise. The situation has me anxious and tied in knots. Any advice at this point would be greatly appreciated.