An NDA protects your confidential information by preventing the recipient disclosing or misusing that information. The question is, what if the information has already been disclosed? Can you stop anyone to whom your counterparty has disclosed that information from using that information for their benefit? The issue is particularly pertinent if the information is disclosed to one of your competitors and that information represents your competitive advantage.
An answer may lie in copyright. That may not be possible, though, particularly if it is just an idea and is not expressed in a document that you can prevent your competitor from copying or exploiting or is in a document not of your own composition or the IP in which has not been assigned to you. You then have your NDA, but most NDAs are deficient in that they lack the provisions to address this scenario. In this video, Martin Algie discusses how you can draft your NDA and the prophylactic measures you can take using that NDA to set up a tort of inducing a breach of contract.