Well, here what you do, Im 20 I have been through everything you have just posted about, the best advice I can give is, call the cops on your dad, you and your sister do not need to grow up with a low life father like that. Especially if your sister is in therapy becuase of that. You do not need that, and neither does your sister. Your dad should care about you more, and not be so abusive, I can tell you its most likely the drugs that are doing it to him, maybe if he will clean up, then the relationship with him will improve. my AIM is DJlotus03 if you ever wanna chat. I hope everything works out with you.