I would say it was a foolish and regrettable thing to do. I'm glad that you'll never do it again. I don't think it necessarily makes you a bad person, however. I'm generally sceptical of the idea that one, isolated act (even an evil one - which I don't think your action was) should forever define someone as a "bad person" - though really it's hard to make such firm categorisations when it comes to most humans.
Importantly, you were still a child when you did what you did and it does sound like it came from a place of curiosity. For those reasons, I think you deserve to cut yourself some slack and move on - or, at the very least, not spend all day every day thinking about it.