Sister's reaction to my ADHD diagnosis ruined our relationship - How to fix this & should I tell our parents? - UPDATE
Thank you so much for everyone who responded to my post last year. I didn't manage to respond to everyone, but I really appreciate all the advice I received.
After my post, I didn't end up telling my parents about my diagnosis. Part of me wanted to, but I got too scared thinking about their potential reaction. All my life, they have seemed to acknowledge that I'm somewhat "special" and struggle with certain things. However, I'm not sure if they would be willing to accept that the cause of it is ADHD. Instead of telling them, I made an effort to talk with them more, and that has brought us closer. I no longer feel the need to tell them.
As for my sister, she kept my diagnosis a secret, and we continued not to talk to each other.
Then, out of nowhere, she reached out to me a few weeks ago and wanted to talk. We ended up talking over the phone for over 4 hours. She has now come in terms with my diagnosis and was supportive. She cried and sincerely apologised. It was a very healing conversation, and I'm happy to have my sister back in my life. She is not perfect, but neither am I.
In the end, I didn’t have to do anything, and it all worked out. Hurray!