My father is cruel to my mother

I don't even know where to start. There's so much to say. Sorry if this is long.

My father yells at my stroke survivor mom, who is bed bound and has severe apraxia of speech and thus is nonverbal. She understands everything. She is in constant discomfort because she is bedbound. He's a narcissist (yes I know the word is over-used but he is one). He and my sister (who lives with her husband and is his "flying monkey") talk about me behind my back and gossip like mean girls, even though I do 80-90% of the work for my mom, and ALL of the important things like setting up her G-tube feeds daily, administering meds via the G-tube (5x daily) and changing her multiple times a day, in addition to grooming, physio, massage, and giving company. Sister doesn't help and judges me from afar. The two of them talk and text about how awful I am, refuse to respect my authority on my mother (I was in the hospital every day advocating for her for 7 months, liaise with all her doctors and the allied health professionals, learned everything related to nursing for her, and have given up everything to take care of her now at home).

My dad hasn't always been kind to her and he resents her now. Yells at her when he doesn't think I'm listening and says abusive things to her. I'm not talking about losing his temper because of caregiver burnout. He's a cruel person. She's sweet and kind and did everything for this family for over 50 years (I'm in my 40s and I don't work now).

I didn't even know he was a narcissist until about 5 years ago, when I stumbled onto an article about emotional neglect in childhood. I worked with a therapist and I came to realize what he is. He and my sister have scapegoated me and I think my mom was the only one stopping their cruelty but now she can't talk. I have zero emotional support from him or my sister. I don't really have anyone except my long distance boyfriend and he is getting tired of my tears.

Right my dad is feeding her and yelling and snapping at her because she won't eat faster (she's allowed to eat a small amount orally for quality of life). Because she has apraxia she groans and shouts as communication. NOt gonna lie, it IS annoying. But when I feel myself getting annoyed by it, I tell her I gotta pee, and then I go elsewhere and calm myself down.

When I tell my dad anything, when I try to get him to slow down or give smaller bites or get him to remind the Psw to not put the diaper so tightly on the 1x/day when he helps the Psw change her, he makes a face and rolls his eyes.

Just today I needed his help when changing her with the Psw, because I had to apply medicine to her thigh. I asked him to hold her thigh and he did it in the wrong way, causing her to scream in pain. When I told him nicely to please not do it like that because it causes her pain, he gave me this look. It's the look that says "how dare you talk to me like that in front of people." He's more concerned with me correcting him, than he is about causing her pain.

I'm in constant physical pain and have fucked up every joint and muscle in my body. I love my mom and she needs me so I do it. But I can't take my dad's cruelty.

This whole thing has laid bare the truth about my family and the illusions have all fallen away. I'm so disgusted with him.