Welcome to Webmaster World! We hope you find this a useful place to hang out!
Some of your wording is a bit vague. What exactly did you ask her to do? Was it in fact the right thing to ask for?
I'm wondering if there are practical reasons for her apparent hesitation, rather than a lapse in good faith. Among other things, do you have your own account with a domain registrar? That's not clear from what you said, but if you want the domain transferred to your control there needs to be an account to receive it. The steps for the transfer might take a few days, but it's not complicated as long as both parties know what they're doing.
Be sure you make regular backups of the site's content, which is good practice in any case. If things did reach the point where you decided to move the content to a different domain, do you know the steps for doing so?
Lawyers do have their uses, but I suspect that some technical clarification would be more help here than calling in the lawyers. At least, not yet ...
Above all, don't get mad and fracture a friendship on the basis of something that you're not understanding accurately. That would be lose-lose in every direction.