Is it legal for a Union rep to share information from a former employees personal profile?

My husband was terminated from his position with a reputable company and was in the Union. He pays child support and when he was terminated, he went to child support recovery to get his payments lowered. We are in court right now, and my husbands ex's Father works for the company he was terminated from. We received an email from his ex's lawyer. His ex's Father emailed a Union rep asking to have my husbands file from when he was in the Union. That Union rep shared information that pertained to my husbands file and they submitted it as evidence for court. No legal documents, just a shared email from an employee and a Union Rep. Is it legal for an employee to request a formers employees personal file and that Union rep to share a former employees personal information from their employee profile?