How do I best cope?

My mom is 90 years old, suffers from pulmonary fibrosis, copd, asthma, and cachexia.  She is now between 68-70 lbs and is only 5 feet. This is a woman that lived independently until about 4 months ago. She has had a steady decline since my dad passed 3 years ago (she was his caregiver up until the last 3 months of his life). Right now my mom is in a skilled nursing facility after going back and forth twice and to the hospital twice. I was trying to care for her in her home with caregivers (when i work) and I had to leave my home and husband temporarily and move in with her). She can still walk with a cane but for extremely short distances and is totally winded after little activity. She goes from being pleasant to me to hateful when she gets angry about her condition and state of things. She is also on hospice. Today she called me at 6 a.m. to demand that I go and get her and take her to her regular doctors (30 minutes away) because she did not feel good and had a sore throat. She said she would not ever forgive me if I didn't. They have access to doctors at the nursing facility and also there is a hospice doctor and everyone works together as a team. I am just at wits end and almost hyper ventilating as I deal with her increased tantrums. I'm 64years. Not sure what to do or what to expect with her current condition. She is declining but I have no idea what road that will take. It is also hard when she lashes out at me. I'm an only child, work full time, and have been accommodating her for years. I am trying my best to do what is best for her and running her back and forth from home to hospital to nursing facility is not in her best interests. How do I best cope? I love my mom but she is unhappy with the state of her life (and I don't blame her) and she never wanted to be in this situation.