Unfortunately your offense is not tolerated in the U.S. too well. Depending on the severity of the offense, you may get a slap on the wrist or permanent record which may affect your admissions possibilities to colleges. The teacher is duty-bound to inform your parents because he/she wants to make sure you and your parents are aware that is not to be repeated and if not corrected, will only result in more serious consequence. You need to prove that you realize the gravity of the offense and not try to hide it from the school or your parents. I know it is not an advise you would like to hear but you need to realize that taking short cuts in life will not always help you succeed. Be honest with yourself and admit your fault and let your teacher and parent help you overcome the temptation and do your best for your future.
I know what i've done is wrong, but i was so pressured that i had to do it, the teacher is actually one of the best teacher in the school, for me. I just need a way to apologyze to him, but i don't know how. Thank you for your advice!