I can't believe your dad registered you for the class hope you didn't break anyone's leg cause after the whole training you'd look all-powerful and unstoppable.
People do take advantage of those who hardly talk, those who can't defend themselves outside, in your case you did well by telling your dad about it, some children won't they'll be enduring the whole bullying thing till it becomes so unbearable.
I didn't break anyone leg o, and my dad had to do that so I can overcome my fear. But you know some kids are just so bad. I only trained so I can be good for myself.