I think you need, really need, to talk about him to someone. His life, his death, everything.
You need to process this mentally and sort out all the emotions. When someone we're very close to dies it does leave a void. There is something huge missing in your life when you lose someone like that.
When you move on it isn't that you forget and pretend the person never existed. You just have to go on with your life. It's what we do. We're still alive. The people who have gone on wouldn't want us to stop living. If the situation had been the reverse and your brother was the one alive... you wouldn't want him going through what you are putting yourself through. A lot of times when you talk, one thing leads to another and sometimes something really important comes out and everything becomes clear and you see things different. Or you just get things out that need to be out. Grief can be a long slow process but you need to start the process. If you keep it all inside and don't deal with it then it will eat you up.