What can I do if a nurse revealed confidential patient information to another party?

Such an action on her part was in violation of the principles of doctor-patient confidentiality, by which she is bound in her role as a nurse.  As JMA says, it is also a violation of HIPPA laws which are very strict about these things.  If you feel that the stress you endured as a result of this violation of your privacy rises to such a level as to merit damages, then you should consult with a lawyer in your locale to determine if you have a cause of action to pursue. 

Many states have statutes regarding the violation of the HIPPA laws, as well as common law liability for failing to keep information confidential.  I suggest that you write a letter to the hospital indicating that the nurse is disclosing private information about you and that it is a violation of the HIPPA laws and confidentiality rules rising to the level of intentional and/or negligent infliction of emotional distress as there is no basis for the nurse to your personal health info to other people.  I suggest that you hire a lawyer.  Most lawyers will meet with you for free the first time.