Purple,
I know exactly how you feel and suspect that you are going through one of the hardest times of this disease, where it makes no sense to you, where you don't want to accept it and where it just hurts and hurts and hurts with no reprieve.
I went through those kind of feelings for 3 years and it nearly took me out, I was wavering on the brink of depression (my doctors were trying to tell me I was, but I did not want the label and get a tad frustrated with the lack of difference between being depressed as a mental illness where there is no apparent cause of the depression except a chemical imbalance and being depressed because you have something really frikken difficult to deal with, so sad, and so impossible to fix!). What saved me, might be completely different to what will work for you, but keeping so busy I hardly have time for any relaxation, worked for me. I now study University full time, work shift work full time and see Dad at the home (he's been in one since April) every day, with the odd missed day. I am not recommending my madness, and no doubt I have gone to the extreme, but I did find that I had to keep busy and have other comittments other than my father and that took my mind off my father.
I am in my last semester at University now, will graduate in December, and I finally feel that when I finish, I will be okay. I am passed that point of not wanting to get out of bed in the morning. I see the future as a wonderful thing, I am still devastated about Dad, but somehow I have come to terms with it and am happy in that at least, if he were able to understand what I am doing, he would be proud of me.
So my thoughts are with you and I hope you too can come through this, it will be hard, but there is light at the end of the tunnel. Try not to be angry at your Mum, she is fighting the toughest battle there is in life, and believe me, if anyone should have been able to beat it, it was my Dad, and yet 5 years on and Alzheimers is still winning. So she is not intentionally letting you down (I know you probably already understand this, and I do understand that you feel angry anyway). Another thing to remember if it appears as though she just gave in, Alzheimer's affects the brain, which means that it affects the chemicals in our brains that help us strive, fight, and not be apathetic, without these chemicals your Mum may appear not to care, again it is not her it is the disease that has changed her. So if you have to be angry, perhaps doing what I do will help, be angry at the disease, hate it with a passion, look for ways of fighting it for your mother and others who come after her, treat your mother kindly to spite the disease, revenge the disease by not letting it win in beating you as well as your mother. Enemy, I name thee AD!