Caregiver to a friend

I feel like a fraud writing in this group but I’m struggling right now. My best friend moved in with me a couple of years ago because she had to sell her house. It was supposed to be temporary but it has lasted a lot longer and during that time her health has deteriorated. She has fibromyalgia and central sensitisation syndrome and is in pain a lot. It’s meant she struggles to drive, walk anywhere, lift her dinner plate etc etc. So I’m looking after her. I’ve gone from a life of independence and coming and going as I please to one where I get a guilt trip if I need to go out, even if it’s just to buy food for both of us, because she can’t do it herself. She does manage a trip to her mum once a week but saves up all of her energy for this and so doesn’t get to see her friends etc. She was also independent and busy and her life has been stolen from her. She is (understandably) angry and upset a lot of the time, and it’s often directed at me. She loses her temper so quickly, it’s becoming an increasingly difficult relationship and I can tell it’s affecting my mental health. She wants to continue living with me and I’m happy to do this so I can help her rather than have her back at home with her elderly mother, but not if I am screamed and shouted at every day. I don’t know why I posted all that, guess I just needed to get it off my chest!