>>I am thinking of just deleting the project and not shipping him my source code.

I see you got your half payment.

My advice at this point is to stifle your usual good instincts and NOT ship the source code, ever. You would be rewarding his bad behavior, and that of course, is bad news for the next guy.

If he asks for it, insist on ALL your money.
Cash the check in person at his bank - don't allow any stop payment nonsense.

If he says you are breaking some agreement, that is exactly right.
It is the standard of behavior that he set.

If he takes you to court, it would be fun to tell the whole story to the judge.

Best,
Michael Cummings