I know it’s only going to get worse but my elder grandmother is driving us CRAZY, what should I do?

I really don't know how to start this out, but I'll just begin with details. My grandmother will be turning 89 within the month and she has had Alzheimer's for the past 3 years but during the last year, it has got incredibly worse. My father, who is her primary caregiver has been staying with her non stop for the past few years. She used to be able to stay by herself during the day that way my dad could go to work, but now, she can't even stand to be in a room by herself let alone dad leaving her for a few hours. So he has been without a job for several months, instead he has to sit here and basically be aggravated by his mother 24/7 and it has driven him crazy. She doesn't remember a thing, it's like we have to answer the same questions over and over again or tell her the same things throughout the course of the day. I have been living here at my grandma's for the past 3 months because I had a motorcycle accident which my foot had to be amputated so I've been here taking it all in myself along with the other worries in my life. Honestly, it's even making me go crazy, I seem to be on the edge all the time and ready to blow off on anybody. But you have to understand my grandmother, she has always been hard headed and stubborn. Now it's even worse, trust me, we try to be good to her and we are but she pushes your buttons with the constant nagging and doesn't even realize she's doing it. She doesn't even think she is at her house (she's lived here 30 years) and every other night she doesn't even remember who we are. She goes around the house shutting doors, unplugging stuff, turning stuff off, and we tell her to leave it alone but it just doesn't help, her brain just wont let her remember it. Like I mentioned before, my dad is going insane. Mind you, my father has always had a temper but within the past year his temper is like a stick of dynamite ready to explode. He gets p'd off and calls my mamaw a b*tch and tells her he hopes she dies or he hopes he dies first. He doesn't mean it he's just mad but he even says this stuff in front of me and it just depresses me. I tell him to stop and try to explain to him that she can't remember anything but his excuse is 'I havent had a life in 4 years' which I can't argue with that because he has not. But don't get me wrong, my Dad is a great person, he's here to take care of and he does, he's good to her...until she starts talking out of her head. And she gets mean, and her smart attitude comes out just to p* you off even more especially when your trying to help her like get something to eat or make her something to eat an she says she aint hungry or she just ate and us knowing that she hasn't ate a thing. A nursing home is out of the question because she wouldn't survive without us. I've tried to explain this situation the best I can and Im sure i've left out a bunch of details and other things but hopefully someone here can enlighten me on this subject and how to help. I know that the problem is just going to get worse but is there anything that can be done?