Can I sue a hospital for disclosing confidential information?

Invasion of privacy includes the public disclosure of private facts.  The issue here is the basis upon which the attorney obtained your medical information.  A subpoena to obtain medical records is a routine procedure.  If that is what occurred here, you would not prevail in a lawsuit for invasion of privacy because a subpoena or other court action would supercede your right to confidentiality of your medical records.  Pursuant to the subpoena, the hospital would have been required to release your medical information.