Im guessing your old enought to take care of your sister or shes old enought to take care of you or your living with a family member/close friend...not in a foster home..
Your probaly under a lot of stres & you dont know what to do...my advice is say something to your dad & those are serious drugs so if he doesnt quit (for his help he needs)go to someone you trust,if your dad trys to hurt you in any way its serious & involves the piggers.
good luck hun
-*Amy