I get along quite well with my younger sister, I even consider her one of my best friends. It's important to note before I say anything else that I have super severe adhd and dyslexia, parents did not allow me to pursue treatment until I begged for it at 13 years old. Those problems coupled with debilitating anxiety and depression made my mental health professionals (including a social worker) reccomend pulling me from school at 16 almost 17 years old. They told me I needed to take a mental break for a few years. 

So yeah, I never graduated high school. It's embarrassing and I've never told anyone outside of my family aside from health professionals. 

Back to the main problem. My younger sister, she's an awesome person, but for as long as I can remember she's always been aggressively competitive and accidentally condescending. I've always loved to share stupid little medical facts with my sibling because the human body has always been fascinating to me, and she always says things like, "Look, OP is trying to say something smart." And it just hurts so much. She graduated high school earlier this year and got into my dream college doing my dream career (nursing), and she's always bragging about it. And when I said I'd possibly be joining her next semester after I finally get my GED, she said, "No, I'll be atleast two years ahead of you by the time you get in. You won't be able to get a good SAT score and skip pre nursing, that's way too hard." She always acts like it's embarrassing for me to be any kind of close to her intelligence level...

I want to talk to her about how I really don't appreciate the jabs and competitiveness, but at the same time, I'm scared of hurting her feelings. It's just making my mental health get worse, I have no confidence to move forward academically because of the things she has said to "joke" around, and all of the bragging.

I don't know how to talk to her about this, but I know I need to if we're going to keep having a good relationship in the future. Any advice is welcome, I'm feeling lost and can't seem to find my voice.