Cutting isn't that strange anymore. I was a cutter; my wrists are ruined with scars also.
People oddly don't ask that much. The only one's who've really noticed/asked are girls I start seeing regularly. When they do ask I don't worry; I just say I was a wrist-cutter when I was younger, that's all.
My family also know that I was a cutter because I got thrown in a suicide ward as a teen and my parents told everyone. But! If they didn't know and it was a family member that asked, I would also be honest, and just say, "I would cut myself when I was younger." And that's it; no need to expand on it. If they're curious tell them to google it because you're not interested in talking about it.
It's never been a big deal when I tell people about it though. Wrist-cutting was sort-of the "in" thing for a while, so lots of people of all different shapes and sizes have self-inflicted scars on themselves. It's not a big deal, really.