I know you've lost someone and it hurts. You have know him all your life. You cannot control the depth of a wound another soul inflicts on you.
Witch is why I am NOT here to tell you tomorrow is another day. The sun will go on shining. But it's okay to be hurting as much as you are. What you ste feeling is not only complete valid but necessary- because it makes you so much more human. And though I can't promise it will get better any time soon. I can tell you that it will-eventually. For now, all you can do is take your time. Taka all the time you need.