I have a lot, and I mean really a lot, of old self-injury scars which are obviously not accidental. I'm visiting family for the first time in many years, and when I met them again my two nieces noticed the scars. The youngest asked about one big one - "what's that?" - and I just said it was a scar from a cut and left it at that. But it's not a good answer and since we're all going swimming tomorrow and they weather's way too hot for long sleeves and long pants, I worry that they'll ask again. They're 7 and 9; what's appropriate to tell kids that age?

[Their parents are not a help here, they perpetuate stigma, not fight it, and won't discuss my mental health issues with me.]