I feel like a failure

This will sound pretty dramatic probably.

I‘m had my high school finals this month. I studied my ass off to do well in the exams and have been putting much time into school to have straight A‘s (for study programs which have admission restrictions). After 3 out of 4 exams, I feel like I just failed. The first exam went well and hopefully won’t be that bad. The second and third one however..
I just wrote down nonsense after nonsense after nonsense and it makes me so angry because I put so much god damn effort into studying. The worst thing is that I know it’s my fault, I could’ve done better but in the end I didn’t. Maybe it’s just my head playing tricks on me and making me overreact, but it really affects my mental health.. I haven’t been in a good place mentally this year and this whole thing makes everything worse. It’s taking me back to a very bad stage of my life 🥲