Hey there @rainfrog welcome to the forums. Very glad you decided to jump on and talk about what you're experiencing at the moment. You say that it is trivial, but honestly if it matters to you, it matters, and it is obviously having quite a big impact on you. That it is so stressful you are crying, and that you are saying these awful things about yourself, tells me that it is well worth getting some support for - so well done for doing so. And also, you're not at all dumb or pathetic for struggling with your school work. You're not a failure, because you're still trying.
Is there anyone you could ask for some extra support in maths? Like a tutor, or some kind of learning support from your school? Even having a chat to your teacher might be helpful. And a school counsellor might be able to help you manage the feelings of distress you're experiencing. We have some resources you might find to be a helpful read - Failing a course or subject could be a good place to start, and some coping tips.
I hope this helps you, and of course please feel free to use this space to vent, talk more about your experiences, and connect with others who may be experiencing similar things.
