I'm guessing the people who comment are people who know you? It's tricky, would agree with Adriana that having a standard answer might help.
I showed scars when on holiday last year - a few people (strangers) stared but on the whole it was okay, probably because everyone was just doing their own thing. With people I know, those who've I've worn short sleeves in front of I've briefly explained to "I have scarring" first.
Sorry this wasn't a very helpful reply! I've never been asked how I got them as like you, it's obvious (or so I think).
Good on you for being so brave though x