What would you do? Tell your mother about all the bad things your sister did or keep those evil little secrets

[TeeJay]

Well that is a hard decision. I had to keep some secrets about my older secrets when I was your age, it's just a part of being a younger sibling. If you are worried about your sister, you should tell your mom. And tell your mom in a way that wouldn't make it obvious to your sister that it was you. Like tell you're mom about her while she's out, so when she comes back they can catch her. And if you're sister finds out that it was you she will be pissed, but she'll eventually forgive you. You were just worrying about your sister, and there's nothing wrong with that. Good Luck!