Self-harm scars at work

Hello, I'm currently working in a school as a pastoral assistant and would really like some guidance on what to do... I used to self-harm - 11 years ago. I have scars on my forearms and was told a year ago by the school that I must keep my arms covered at all times. Since then I have been fighting for the decision to be changed after enduring uncomfortable heat (almost passing out), watching colleagues wear what ever they like to work and knowing that I am being treated differently to other staff members. The whole situation has led to physical symptoms of anxiety- dizziness, shaking, heart palpitations etc- all of which I've not had since my depression 11 years ago. My scars are faded and I believe they are barely visible, I believe the person asking me to cover them up has never in fact seen them before but has heard through my manager. When I first joined the school I asked my manager what he had thought about being able to uncover my arms at school, he said he thought it was a sign of strength and would show the students that you can get through dark times and become something you should be proud of, it would also show empathy and understanding. However, after the last year, I am left feeling deeply ashamed and self-conscious. Their argument is that it could trigger a child to begin self-harming, I completely disagree with this, as a self-harmer, I would always go to a person who had scars for advice, support or just someone to listen as I believe there would be a mutual understanding of emotional turmoil. I also strongly believe that as a society we should learn to accept that people go through mental health issues and it is possible to come out the other side. There is so much at the moment about tackling the stigma, but I think they are creating more. I do believe that fresh cuts could be a potential trigger, but not scars. If anyone could advise I would greatly appreciate it.