So let me get this straight, you guys left your money in your room, your stepbrother waltzes in and takes your money and somehow it’s finders keepers?

If your mom has that twisted logic in her and your dad isn’t willing to step in, then they’re both twats. You’ll leave in 2 years on way or another, get your little sister out too. Some families just aren’t worth actual revenge. They’re too blinded by their nepotism.

However, never forget this. Never forget the day when you realized your mum would side with someone that’s blatantly wrong and your stepdad not stepping in. 10 years down the line, if these people try to get stuff out of you by saying “he/she’s family!”, always reply with the “remember when I was 16 and this happened?”. Not worth it. Cut contact with all but your stepdad.