How do I deal with a parent who "hides" symptoms (forgetting things), is OCD, and wants you to move out?

I "live with" my father. Not because I financially need to, but because I promised my dying mother I would "look out for him" because she said, "he cries to me Angela, he's forgetting big things and is scared he's going to be like his mother. Promise me you'll look out for him" so that he maintained his pride and I was able to keep a promise I made, I asked him if I could move in with him for "help". Maybe that was a mistake, I don't know. He is pretty much self-sufficient, he drives, he pays his bills etc. But if I don't "stay on top" of him, he won't take his medication or he gets confused and doesn't take it correctly, he won't go to the doctor when he has symptoms of something, he won't eat right, he isolates himself and will drink alcohol. I know he is forgetting much more than he tells me, but I've harassed him to the doctors office, we have had every medical testing done that can be (no brain lesions, no nothing) and there is no physical evidence of dementia. He is super ultra critical, of EVERYTHING I do, I walk into a room and he immediately starts scowling ( no exaggerating here), he is obsessive compulsive about cleaning, I can't even leave a deodorant out on the counter in the bathroom! He makes comments about "when are you moving out" - constantly. He HOUNDS me to the point that I've pretty much thrown all of my possessions away because "you live like a pig" ( in his room is a bed a dresser and a table with a clock that's it.) He has NO hobbies, no enjoyments, he collects nothing and that's how he EXPECTS me to be also. He habitually goes through my bedroom, my drawers, my paperwork, even my car, my trunk and my glove box! I give him $300. every two weeks for "rent" plus I purchase food, laundry soap etc so I'm not just "living off him" like my sister believes. I feel like he wants me to disappear, as a human being. My bedroom used to be my "solace". The one place I could get away from him and relax, be happy and now he's taken that from me too. When I moved in with him, I went out of my way to make sure I didn't "invade" his house. I didn't change things, I didn't move things and made sure all my things were in storage or in my room. He relentlessly hounded me about my room and my things in it and he finally got in my room by claiming that it needed painted and the carpet changed. So now my room is pretty much bare of anything except a bed and a dresser. Financially, I can leave and trust me I want to (he isn't passive about wanting me out either) but I know what will happen when I do and I'm in a moral dilemma. I miss my things, I miss my furniture, I miss my fish, I miss my "home", I miss having a home, I feel displaced, out of place, unwanted and abused. I'm tired. My sister is his emergency contact, even though I live with him, my sister is on his bank accounts, my sister is on his will and she has told me, mincing no words, when he dies shes throwing me out to sell the house and pay his bills off because "she's not being responsible for him". She has told me he will never live with her and she will put him in a nursing home. She lives 2 hours away and is pretty much non-existent in all this. I am depressed and to add fuel to the flame my 17 year old daughter also lives here and has to endure his endless maliciousness and anger. We can't "hide" enough for him, we leave no possessions out, only our shoes in the front hallway and he complains about those. I know if I leave I wont want to come back, I won't want to visit or check on him or anything - the wounds he's leaving are deep and gushing. I don't know what to do.