Dear Gao,
you do not need to apologize to your classmate.it was his fault to bully you and other people.you do the right thing to give him a lesson.
what you should do is not say "sorry",but talk with him.you should tell him that bully others is wrong.if he don't change himself,he wouldn't get a true freind in his whole life,while he meet trouble,no one will give him a hand,and his future will not be good.
and if him beat you again,you'd better run,do not fight him again,it does no good to you.then you should talk with his parents,tell them they should keep an eye on their child.if this do not work,ask you friends,teachers for help.when you need me,call me,i will come very soon.
yours friend