I'm fucked I i have Physics exam on 17th and I don't know a thing

I'm currently in 12th English and Marathi exam went smoothly but I'm way too stressed about the 3 subjects i really don't know what to do rn. I wanna kill my self but it's gay. So I'm hanging in there are 12th marks really important. I just wanted to travel the world will my dream would come true or I'm going down with my 12th grades.i Have got a wonderful mother but I think she got a failure as a son. I don't know wth I am doing with my life. I really wanna cry rn. But I am trying please tell me your experience after 12th when you'll got low grades