It's not yout fault. Your mum is a horrible person for saying "finders keepers" in response to him stealing your hard earned money. She's actually complicit as she allowed him deposit it into her account. I get the feeling maybe he found it, told on you, and she decided to let him spend it to punish you for having a job. Your stepdad sounds like a pathetic, spineless coward.

None of these people deserve your respect or loyalty. Well your sister does obviously, i mean the people I mentioned in the above paragraph. They don't deserve anything good from you.