triggered by friends self-harm scars

Recently, my friend that I live with started self-harming again. The first time I noticed the new scars, I felt really panicky and had to leave the room (I could feel a panic attack coming on), I also fell into a dissociative state for a good few hours after that. I feel conflicted because I want to be there for my friend, I also don't want them to feel self-conscious or embarrassed about the scars (I wouldn't dare ask them to cover up or anything). BUT, I feel the need to look after my own mental health too, and find it really difficult to be in their presence when the scars are in full view. The stupid thing is I feel like I have no right to be triggered by the scars because I have never self-harmed (although I do have depression and have felt the urge to in the past). Any advice on how to approach this situation would be much appreciated! Should I tell them how I feel? Should I keep it to myself and find a better way to suppress the panic that doesn't require me leaving the room.