Hey friend, I'm sorry that things are so hard for you right now. I almost didn't graduate high school too, and I remember thinking similarly at the time -- I thought it was the end for me. Everyone around me seemed to be telling me, "this is so easy, why can't you do this if it's so easy?" But, honestly, high school is so much harder than most people give it credit for. I remember my high school experience being so stressful and difficult. Trying to balance classes, grades, friendships, trying to fit in, worrying about the future, all on top of dealing with an abusive family and undiagnosed mental illness? It was horrible, and there were a lot of times when I thought I wasn't going to make it. If you couldn't handle it, it doesn't mean there is something wrong with you, it means the system is deeply flawed and broken. It has been for a long time.
But also, IMO high school really isn't that important in the grand scheme of things. I know it seems like it's the most important thing you'll ever do while you're there, or at least it did for me. But truthfully, the second I got out of there I could look back on it and say "you know what, that whole thing was really weird and fucked up and kind of stupid." This doesn't have to be the end for you. I don't know all the details of your situation, but if you're in the US there are a lot of opportunities for you to have a second chance -- you can study for your GED, or you might be able to continue studying next year to finish your HS diploma (my school had a 5th year program like that), or there are even online programs nowadays that allow you to get your diploma. You can go to community college or trade school if you want to -- I'm at a CC right now, and for the most part it's been a great opportunity to start over and figure out what I want to do. It's amazing how much less dumb shit there is here compared to high school. Sure, I still struggle here and I probably will in the future, but it's so much better here because it's okay to struggle. I hope you will be okay, friend. I don't know everything you are dealing with, but this doesn't have to be the end for you if you don't want it to be.