My supervisor was given medical information about me in confidence. I now find out that the supervisor has shared this information with everyone in the office without my permission, is he liable for releasing this information ?

HIPAA laws can only be violated by the medical profession. If the doctor/hospital told your supervisor without your permission it is a violation.
Your supervisor telling everybody else would fall under whatever your works policies are.

No HIPAA violation here. YOU volunteered the information. Depending on the circumstances under which you gave out the info, there may have been some ethical or work rules violation.

There may have been some ethical violations depending on your company's policy, however, this is not a HIPAA violation. Think of HIPAA as doctor/patient privilege.

Now, how did your employer come about the information? If the doctor passed it along without you signing a release of information, then yes, it would be a violation on the part of the doctor, but not on the part of your employer.