only you can turn you into a violent person. Its aan attitude thing, as long as you keep the attitude that it is not ok to use violence except in self defense (or whatever your beliefs are) then you wont suddenly morph into rambo. Knowledge is only knowledge.
In terms of hurting someone or getting hurt, it is a contact sport. When you participate you are accepting the risk to yourslef, as is anyone else in your class. Now if you were teaching yourself id advise not to, but as you have instructers they are not only teaching you the moves but also how to control the moves which greatly minimizes accidental injury.
I say have fun and give it your all