Please help, I'm at the end of my rope from manipulation?

Please help. I'm a 31 year old adult daughter of a psychriatically ill 68 year old mum. I dont have any siblings. My dad and her have a bad relationship in that she mentally abuses him, so he leaves her house at 10am every morning and does not come back until 8 or 9pm at night, he has his own place a half hours drive away. She is cared for in every practical way, financially, clothes wise, food and has her own independance and car. Her mental illnesses manifests itself in separation anxiety and a 100% lock solid idea in her head idea that my role is to give up my life and my boyfriend (who i live with for 8 years) for her, and she drives this home to me every time i meet her. She doesnt like my boyfriend and has bad mouthed him to people and i cannot bring him home to her house (where i go every 3 weeks and xmas, easter and any other special holidays..i have to be separated from my partner). She has fought and said nasty things to her family (brothers and sisters) and now they all exclude her from family events..so she has no one. She soemtimes turns up at family events and then they ring me and tell me the nasty things she said or done even though i cannot control where she goes. that has lead to me cutting those aunts and uncles out too...as they have never been a support to me only to tell me how nasty she behaves. One aunt rings me up and tells me word for word the nasty things shes said about me and to her and then tells me not to repeat it as shes doesnt want to get ate by her. This leaves me so upset. My dad says i should do more aswell, although i do all i can with her. I've spoken to her doctors and nurses and they say she is just dfficult and wil not change and she is under their care. She tries to control me and people just tell me i'm an adult and to stand up to her wickedness, but i feel shes acting out of desperation and i dont want to upset her more. My dad then also says i'm not to stand up to her and make his life more difficult. He says hes the one dealing with her dailly while i live 60 miles away, so he thinks i should be doing more. Shes coming to me for the weekend and my skin is so bad...please help me.. She even gets so far as accident and emmergecny and gets checked out over and over again in attention seeking behaviour taht keeps everyone worried. Please help