I think i triggered my friend and I feel so guilty

He's already had sh issues but a couple days ago I wore short sleeves in front of him because it was very very hot. I was afraid that I'd trigger him because I have scars that are still pink and visible, but I didn't really think it'd happen. Now he's confessing that he has hurt himself. If I'd just kept my long sleeves on and fought through the heat this wouldn't have happened.