First, a patient cannot sue for a violation of HIPAA. There is no private right to do this. Even if the patient choses to bring a claim for a violation of his or her constitutional right to privacy it doesn't sound like there are any recoverable damages because none occurred. In terms of the Board, mistakes happen and you have taken all the steps to immediately remedy the error. Although I am not licensed in your state, I can tell you in Florida it is likely that nothing would happen. You are always wise to seek a lawyer who handles disciplinary actions, and you have taken all the right steps. Best to you and don't stress about this.
In general, it is unlikely that a single inadvertent disclosure of private health information could result in the loss of a nursing license. However, Texas has implemented its own privacy law which is much more stringent than HIPAA. The Texas Attorney General can act and investigate on private complaints alleging a violation of Texas privacy law. Beginning in December of 2013, the Texas Attorney General will post a log of investigations on its website.
You and your employer are not liable unless there are damages. Since the recipient immediately returned the document, the risk of identity theft is remote to nil. The SSN was truncated and a person would need the other five numbers to make use of the SSN.
Sign up to receive a 3-part series of useful information and advice about personal injury law.