There is some merit to this approach: continue to assert your IP ownership, but don't take legal action - just preserve the option to do so, if the venture take

There is some merit to this approach: continue to assert your IP ownership, but don't take legal action - just preserve the option to do so, if the venture takes off. However, you'd still want to talk to a lawyer to do this right. Keep in mind that while shopping for a lawyer, you get essentially 30-60 minutes of free consultation (by phone or in person). So prepare a compact summary of the situation (documents and timeline) and then talk to a lot! (You'd be amazed how different their opinions are, so the sum-of-many is worthwhile.)