Disappointed in myself

why there is EXAM in this world??Why they want 2 make us suffer like this..EXAM is making me crazy,stressful n sick!!!!!!Sometimes i really wanna shout out loudly all my feeling n let go all my stress..but it cant change anything.I'll be having chemistry,physics and math exam tomorrow.For math i still have 40% confident but for physics 0%!!!Feel very disappointed in myself..How can i be so stupid!!!This is just a monthly test,how about STPM?How can i face it??Feel like CRYING