Assuming your description is accurate, you should have had %95-%98 of the equity of that startup, and all ownership of the code. She was defrauding you (says

Assuming your description is accurate, you should have had %95-%98 of the equity of that startup, and all ownership of the code. She was defrauding you (says she's taking class, so you enroll, turns out it was a lie, says she'll meet with you, doesn't show up, claims she should get %100 despite doing less than %5 of the work, etc.) and gas lighting you attempting to emotionally manipulate you into thinking you were the bad guy. My response would have been to give her none of the code, she didn't deserve any. But I really expect that she'll get nowhere with this app anyway... she can't get traction with just an initial release, it will need constant work. Her actions are very typical of the "clueless business type" that has no respect for the effort of software development (just pointing out functions not yet done is a prime indicator- they can't be bothered to dig into the project and think there's some value in pointing out the obvious?) Which means she will be a failure with this startup. You would have been better off, I think, taking your software and shopping it around to other MBAs in this class and seeing if you can find someone who will give you a real offer. You could work on the app on the side, and you don't have to give up your permanent job, but even if you didn't work on the app, you should have still owned a chunk in the company that developed it further (assuming it was worth developing further.) But owning a chunk in a company run by someone who is clueless and trying to defraud you is not worth anything.