Well, I never quite made it to high school since I dropped out in 8th grade ;; but I felt this way in junior high completely.
I hated gym so much because of COURSE I was picked last for everything. Nobody wanted me around, not to mention my asthma and tachycardia made it impossible to do anything physical task without dying (and without a doctor's note back then to excuse you, you basically get told by the gym teachers to eat shit). I was only good at dodge ball bcus it was easy to avoid being hit, but when you're the last one standing and can't throw a ball to save your life, you get hit and the whole team hates you, like. You guys all got hit before me, you should be mad at yourselves for getting out so early in the game instead of making me feel miserable for being the last one left! Oohhf!!
I've also had people ask me out as a joke, like, as if I ever believed them. I don't know why they even bothered. And I had close friends in 7th grade, but once 8th grade rolled around I no longer shared any classes with them, I never got to see them in the halls or at lunch, and my closest friend befriended the person bullying me which to this day perplexes me since he knew how much I hated that guy.
Group assignments were the worst cus no one wanted to hear my talk anyway (who would really want to...) so I just kept to myself. At least lunch was optional so I didn't have to eat alone, I just stayed in the student center waiting for time to pass. The friends I had in previous schools didn't even remember me and the ones that did wanted nothing to do with me. It became routine since 5th grade to come home crying everyday and sitting in the dark listening to sad music. That hasn't really changed for me I guess.
I was just such an outcast that when the time came that my friends had an excuse to no longer want me around, they took every opportunity to avoid me completely. When I transferred schools in 8th grade it was the same deal. Miserable, but I got my first bf that year (didn't last long bcus I'm socially stunted and couldn't comprehend romantic love) and somehow it got out at that school that I was self-harming and suicidal and I only ever told a teacher this so the teachers gossip about me too?? (Of course that's true, they used to in elementary too). So I had the fakest people ever try to be my friend like "omg let's go shopping" just out of pity.
I was just something to be pitied. That remains the same to this day... I don't know if I'll ever not be an isolated outcast in society.