My sister is 10 years older. She’s 78 I’m 68. We never got along. Frankly I never liked her. How do I cope?

She moved from Cali after 30 years. I live in a doublewide in PA having been brought here by a dismal and miserable relationship that I ended. I’m stuck here. Can’t afford NYC anymore.
She doesn’t want to be here. It’s apparent. I “retired” last April and immediately fell into a caregiving situation for an old and dear friend. Our lives simply crossed and he needed me. I became an ostomy nurse with only hands on training. He died 6 days after my sister arrived. I was told by a miserable woman that he died because I deserted him. I had every intention of going back but honestly he was more dead than alive. And he knew my sister was coming. I have been on my own only 3 years now outta the last 30 filled with bad choices.
We are polar opposites.
She brought 2 cats into my home and I already had 2. My dog died last year and I want a puppy. Nope. Not happening. Can somebody tell me how to stop my head from blowing off?