Looking for support and encouragement

I am 39 years old and just recently diagnosed as having adhd. I am single but I share a home and life with my sister. Long story short, I believe that my behaviors towards her are adhd based. I know there is more I can do it is just I'm completely overwhelmed. She believes I lied to her about who I was and that I'm manipulating and using her and is constantly angry with me. I can see, after the fact, a parent child dynamic. I feel attacked and nagged and unloved and incompetent. She says she feels used and unloved and accuses me of not caring about anything but myself. She eventually blows up at me and I shut down and then she yells at me more for breaking my promise to be there for her and if eventually ends only when I can calm down enough to somewhat validate her feelings and usually I end up crying and feeling worthless. Am I the only one? Does anyone relate?