Before I issue any advice, I have to say, I'm sorry, that really sucks about your friend man. There isn't a whole lot to be done about that, you just have to hope that it fades with time. Beyond that though, I would say:
1. Maintain control, if you approach things calmly, you have a much better chance of dealing with them.
2. The books can wait a bit. If you don't have the time to write them right now, that is perfectly understandable. On the other hand, it could help you to work through some of the problems you are going through. You have to decide on that one.
3.Talk to your friends. Tell them that the stuff they are doing is ridiculous, and it needs to stop, because it isn't just affecting them, it is affecting everyone. Be a friend, but at the same time, make sure they get how serious you are.
4.I don't know how good you are at multi-tasking and getting things done quickly, but you could try working on homework in school, and during lunch, if need be.
5.Keep your promise if possible. I may be out of line in saying this, but I have found that it is a very good policy to keep your promises if at all possible. Not only does it make people trust you, but I would imagine that you will get some pride from knowing that you kept your word.
6. Personal life. I don't know well enough about this to be too specific, but it seems like you just need to roll with the punches and weather the storm for a while.
In all probability, that is little consolation, but you should know that wounds will heal, and things will get better sooner or later.