Urgent Help Needed! How to get rid of an unwanted family member that lives with you?

In October my boyfriend and I let his 74 year old dad move in with us.He has multiple medical problems such as diabetes, congestive heart failure and more

Just days after arriving, he decided to tell me that my place was to cook and clean and I had no say in anything else, was to keep my mouth shut and do as I was told (by him). I of course responded with "This is my house and your son does not treat me like this and neither will you" Well me standing up to him, made him mad, but oh well, it is my house. I continued his care.

He is a Vet, so I got him set up with the VA Hospital here, and started gettting him excellent care. I was taking him to all his appointments, handling all his pills, scheduling, talking to the doctors and basically all aspects of his care, including wiping his butt when he couldn't. He developed Gangreen in his foot and leg due to diabetic foot sores, and had to have an amputation of his leg above the knee in December.

He continued to occasionally be mean and degrading to me. He also started trying to step in and correct our 8 year old son, yelling at him, telling him that he was stupid, telling him that he is a bad kid, and this continued despite my boyfriend telling him that he is the grandfather not the dad and it is not his place to correct our son or say things like that to him. He then started only doing it when my boyfriend was at work, which left me the only one here to defend our child, but when I would tell him to stop or that it is not his place, I got screamed at, cursed at, called every name in the book, told it was none of my business, told to shut up, I'm worthless, just the maid, and so much more. I would repeately call my boyfriends cell phone crying and mad. When he would get home he would say something to his dad, tell him to stop and then things would be good for a while.
However the other day things got really bad and have stayed consistantly bad for two weeks now. I slept in the other day, because I am so exhausted and emotionally drained. I got our son up late for school and had him getting ready, and went back to my room to get dressed because I had an appointment and so did dad. While I was getting dressed I heard dad yelling at our son telling him to hurry up he was making us late, and it was all his fault, and he never does what he is told to do. I went out and asked what was going on, and told him it was not our sons fault it was mine because I slept in and again it was not his place to be saying anything to our child. He turned on me screamed at me, cursed at me, verbally bashed me, bad mouthed our son, and we argued until I finally walked away and called his son. His son had me leave the phone on speaker and lay it down while we finished getting ready to go. While our son had breakfast I placed dads breakfast and pills on the table but he refused to come eat as he was sitting in the living room pouting like he often does when he doesn't get his way. I finally told him that he could "either act like an adult and come eat so we could go or he could stay home, it was his choice I didn't have time to argue" He ignored me completely. His son told me to go take our child to school and go to my appointment as planned, so I did.

In the meantime after my first appointment and before I got to my second I got a phone call from dad's dr that there was a problem with his blood work and his potassium was at a toxic, heart attack level, so I skipped my second appointment to come home and check on him and tell him that more bloodwork was needed. I was again cursed at and told to stay away from him. The nurse came and took more blood. I offered lunch that was also refused. Then the dr called back and said the level was still too high, dad needed to go to the hospital. I had did get him to listen long enough to let me take him to the hospital, but while at the hospital (I had to take my son cause it was after school) my son was acting up and I was told by dad that I needed to "punch that boy in the mouth then he would listen". I was so mad as this was not the first time he had said this, and I told him that it was inappropriate, and child abuse to say the least.

Once he was released and got home, he went off on his son, tried to tell him lies about the entire thing such as I just left him and didn't take him to his appointment, I didn't feed him, I yelled at him for no reason, ect. When his son told him he was on the phone and heard the whole thing and defended me, then he went off on is son telling him that he was a lier, wasn't his son, was worthless, basically anything he thought would hurt him. His son finally told him if that's the way he feels then maybe he needs to leave our home. He then turned on me and tried to throw me out of my own home, and got mad when his son said I wasn't going anywhere. We called his youngest son in Ohio who agreed to take him back in June, so we were trying to manage until then.