Van Zweden says Swans boss Michael Laudrup was "crazy" about signing the midfielder.
"What a bunch of morons. You sell your best player for €950,000? You cannot do this against the supporters. My whole day is ruined," he said.
"A third goes to ADO, third goes to Toornstra and a third goes to the agent of Toornstra.
"And ADO does not even have a resale arrangement. How can that be?"