What's the protocol for somebody who wants your project files to pay somebody else less for a project?

So I've been working with a guy who's been paying me $15 / hr for animations and some editing. I told him I'm going to start charging him $30/hr now (I started with him early on and have since been able to charge new clients higher prices) since $15/hr isn't worth my time anymore.

He told me to forget it and he'll find someone else and asked that I send him all the source files so the new guy can continue work. I don't feel like I'm obligated to provide him any source files but I also haven't ever been asked for source files before.

What should I do?