Hmm. Heard this story from a friend who was freelance web designer quite a few times. He got so p*ssed at clients doing this sort of thing so often, he quit freelancing to go back to working for someone else. Less hassle apparently.

The point being, get everything in writing, and make sure all contracts are fully watertight, and if they won’t pay, then sack em off and find someone who will.

He won’t pay you, he can’t sue you.
I’d ignore him from now on.

Not really sure what your work is but what if it becomes something of value in his hands . The copyright may be worth some thing in the future and may become an area of dispute. Get your work on your website now . He has not paid for it you have not given ownership of the copyright over to him.