My dad and my stepmom are being really dramatic. How should I deal with it?

It sounds like you are living with your mom and only visiting your dad and stepmom? If that's the case could you visit your siblings after school? If not you may have to put up with them. I agree that it's better to have your siblings in your life and put up with your dad and stepmom than not have access to your siblings. You should insist on your right to see your siblings if you're dad and stepmom try to stop you. I'm not sure what you can do though since it's their house. I would not let them control you with your mobile phone. The best thing to do would be to give it back to them and tell them you don't want it. From your other question I take it you're looking for a job, so you'll be able to afford one soon. It's an impossible situation but you've got your priorities straight and you're on the right track.