How do you deal with an unexpected death?

[Dolla Dolla]

A co-worker and good friend of mine passed away yesterday. I just received a company wide email. Totally unexpected. We had a business lunch not more than a month ago, and everything was fine. Total shock, I could barely believe what I was reading, and I still can't fathom the idea that he's gone. How do you deal with death? It's a bit different when someone becomes sick and there's a possibility of them passing away. But when they are taken from you in the blink of an eye ...? My mood is shot to hell.