Alright, looks like you're going through kind of a rough time right now. Sorry to hear that. I'm going to break up each of these three problems that you are having though to make this a bit easier. First of all, as to your friend moving, I think the best thing to do here is to listen to the old song line, "make new friends, but keep the old." Just because he's moving doesn't mean you have to forever lose contact with him. In this day in age, with so many ways to stay in touch with people, it is absolutely possible to stay friends. Talk to him on AIM, MSN, Facebook, Myspace, the phone, through email...anything. Additionally, depending on how far he's moving, you can perhaps still visit him on occasion. Will it be sad to lose such a good friend? Of course, but you aren't completely losing him. Also, take this as an opportunity o meet new people. There are lots of good people in the world that I'm sure would be great friends. Go meet some of them! If nothing else, they'll help you get past the pain of your friend moving.
As to your friends who self injure, I recommend that you do one thing, above all else. Drop the "it's stupid" attitude. You want to help your friends? It's going to be really hard to do if you have the attitude that they are being dumb or immature. Try to be understanding. Cutting is a way of dealing with emotional pain, which they are obviously experiencing. Help them sort out that emotional pain. The best way to do this is just by listening. Be there for them when they're down on themselves and need to talk to someone. Let them know that you're here for them and you want to see them get through this. Additionally, you may want to encourage them to talk to a doctor about cutting. It is a dangerous habit, and you don't want to lose a friend to this. Getting professional help is an important step towards recovery.
Finally, regarding your family, I think the really important thing to do is to start communicating. What I'm hearing is a lot of lying yelling, screaming and misunderstanding. This can be fixed with better communication between family members. Sit down and tell them what's important to you. Explain that a lot of what has happened lately has been hard on you, and that you want to get things straightened out. I think if you put in effort into fixing things, your family may be more likely to follow your lead and do the same. However, the situation won't just fix itself. It's going to take time and patience and work. You guys need to start learning how to work together all over again.
If you need to talk to anyone about all of this, feel free to open up an account here and send me a message. I would be more than happy to listen.
Take care.