OP, can you clarify why the NDA had not been discussed before building? And did you agree beforehand to her keeping 100% of the equity? If you did, was there a

OP, can you clarify why the NDA had not been discussed before building? And did you agree beforehand to her keeping 100% of the equity? If you did, was there any contract/agreement signed to that effect? Also curious to the course structure and student roles: Did other teams in class form companies? If this more like a regular class project, then I wonder if you could call it a day with both sides retaining a copy of the final report, while she retains the biz details (spreadsheets, etc) and you retain the tech bits (code). She would be free to find another dev to build a new app based on current specs, just as you would be free to find another business person if you decided to pursue the concept. In any case I wouldn't sign any agreement without legal help at this stage.