Is it illegal for my employer to reveal my mental health diagnosis to a colleague?

I found out that, several years ago, one of my colleagues sexually assaulted three women. My knew about this when he hired him. I found out when I googled the individual. My supervisor has a plan for each member of our staff to "tell our life stories". I told him that I am unwilling to listen to that particular employee tell his story as it will trigger my PTSD. My supervisor then told a different colleague that I have PTSD when he found out that she also knows the employee's history. My supervisor has excused the first employee's behavior as "not a big deal". Since I told him I don't want to listen to the employee's story, he has gone out of his way to remind me that I am a subordinate, has scheduled training for a different colleague to replace me in a key role in the organization, and had suggested that I need therapy.