There is a contract for the company set and equity structure.
Regarding legal costs, I've used Pre-Paid Legal's Small Business Plan for a year. It costs $69/month and they do all sorts of stuff (and things like contract review are free). It isn't perfect but it has saved me the hassle of, "Should I sign this? Should I do it like this?" since I no longer have to worry about money when it comes to important legal decisions. URL: http://wserver0.prepaidlegal.com/legalzoom/SBpage2b.html
Also, bear in mind that if he structured the company as an LLC, there's no such thing as an equity-holding employee; she's a principal. He may not even be able to fire her or recover the equity, unless they're on good terms.
In any case, I am just considering that an option to at least try to get the partner to finish the job or at least get some of the costs back.
The development must go on so I wouldn't say pursuing the legal route is the primary goal.
At the moment, I think you need to get an opinion from a real developer who can look at the code and the project design to see how long it would take to get it to the prototype stage. Depending on that I would try to get more funding in order to implement it while at the same time pursuing the legal route and trying to get your money back.
Also, learning Django may seem a little overwhelming at first but it's not too difficult - you can usually find the answers to any questions online.