How did he got your files in the first place?

Secondly, I think you should stay calm and talk to your Dad about the problem. Ask him what's the REAL problem with him doing a job. Other then that, if he's worried about your school grades. Prove him by getting good grades.

Where does he wants you to work at?

I was in exactly same situation when my father told me that you are just wasting your life by freelancing. Firstly because there's hard way to freelance in my country (no paypal) and Secondly, employers here doesn't believe on freelance portfolio. He had few complaints for me that I wasn't studying and I was getting fat. I got back to track where he wanted me and after that I use all my leftover time to freelance.