Hi Kevin. Unfortunately, like a great many people in the world today, you are a victim of the times and the economy. There are thousands of people that are going through exactly what you are, and feeling the same way. You didn't say why you lost your friends but I am sure you will find new ones. Years ago, friend were around for the duration, but not so anymore. Circumstances change that for many of us. You have to learn to find new outlets for friends from time to time.
The good thing I read in your post is that you are at least able to find jobs. There are many much older men that are no longer able to do this. Whenever you think things are bad, just remember they could always be worse. Nobody should feel like they want to die because they lost a job! You are young, strong and healthy, and there is alot to look forward to in your future. You have your college education to work on, which is something to be proud of. Your brother is probably just kidding you or jealous, or both. I see so many posts from kids saying their siblings are mean to them and call them names. It's not like Happy Days anymore is it? Just laugh it off, he's trying to push your buttons, and you are letting him get the best of you.
Hopefully your mom will find a new job soon, and in the meantime, you should lean on each other for support. The economy will eventually turn itself around, you will go on to finish school, find a great job, and probably get married and have a couple of kids. All things you would miss if you were not here.
It's sad that you cannot find some joy in life right now, but I assure you, your life IS worth living. It's a precious gift, to be cherished and experienced to the fullest. What seems like the end of the world today, might totally turn itself around next week, and you want to be here to see it when it does!
Take some time to formulate a plan for your life, go after your dreams, and don't let anyone or anything stand in your way! You have the strength, it's in you...you just need to harness it and go! God bless!