Very tough situation to be in.
Suicide in any situation is a very serious problem to encounter. Your brother honestly seems to be going through a stage. I mean unless you can analyze the situation and him himself, and find out if there is more to this then there seems.
I went through this myself. I've contemplated on many occasions of killing myself, mainly not because I ACTUALLY wanted to kill myself. But because of things around me. Once I had support, and got back on my feet, I never looked back. It's very hard to determine whether or not a person is really serious when it comes to "I want to kill myself". I mean, when I tried, I couldn't do it. Nobody without serious mental illness can actually go through with doing it.
The best thing I would be doing is first and foremost. Tell your Parents. Your family needs to know, once that is done, your family will know, understand and start the process of helping your Brother. If your Brother is suffering from depression or anything along the lines of it. He needs to see a profressional, whether it be a psychiatrist, or counseller.
Your Brother needs to understand that, his life isn't over. Times get hard, nobody is going to go through life without having hard times hit them. That's what makes life.. Life. It helps shape us, and evolve us. He needs to understand he HAS family that LOVES and CARES about him! Whether he wants to sit there and believe it or not. He needs to understand that killing himself isn't going to save him, nor will it "extract" the pain.
Killing himself would only resort to him losing his life he had to live, and it would mean your Mother and Father have just lost a Son they loved and cared about. And imagine if he did kill himself and you never told your Parents?
They could've saved him. You need to tell em' mate. Support, love, and care for your Brother. He'll look back when you's did that and thanks you's once his back to living a great life. That's what familys for.
Goodluck man.