You may have rights, but more facts are needed as to your professional relationship with her and what you intended in working with her. You should consult a copyright lawyer.
This answer is for general information only. It does not constitute legal advice, does not create an attorney-client relationship and is not confidential. If you need legal advice, you should consult a lawyer privately about your particular facts and circumstances.
You should certainly consult an experienced copyright lawyer. Much depends on whether you signed a written agreement with this person, and if so what that agreement says. If you and the other persons are joint authors (which you might be if you both contributed copyrightable authorship to the book) and you have not assigned your rights to the other person, then neither joint author can grant an exclusive license for the book without the other joint author. Any publisher will want to get exclusive rights. Another important question is whether this person listed you as a joint author on the copyright registration.
Again, if you want to protect your rights you will really have to involve a qualified copyright lawyer, who can give you more specific advice based upon the facts and details.
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Your 1st sentence implies that you're "joint authors," and intended to share the copyright to this book. Your 2nd sentence seems to step back from that a bit. Joint authors don't have to consult each other about licensing the jointly owned work, as long as they account to their co-author.
If you didn't intend to be joint authors, and if her contributions weren't sufficient to make her a joint author, then maybe she isn't.
The best practice is to have a written collaboration agreement that spells out the parties' rights, and it sounds like you didn't do that, so now you need to see an IP litigator to discuss the details of your situation.
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