How to grieve?

I can't believe he's gone, its still weird to me. We were friends but not close, and even though I didn't completely get along with him all the time he was still a nice guy. I found out he died today earlier this evening and I was so shocked. After about two hours it hadn't really hit me yet. But now I feel so unconformable, I don't feel like eating, its 2:30 am here and I can't sleep. He was just 20 years old. I'm just still confused, surprised, I don't know how to explain the feeling. Its like. . .my own classmate with all his hopes and dreams, just gone just like that. At this young age while all of us are still alive struggling to finish college, he already knows the truth about the afterlife. The afterlife. I feel so uncomfortable typing this now. I remember that even though I'd given up on a music career, he kept trying to find a way to push me back into making music. 3 weeks ago we had this very long conversation about our future, about our plans. One of those random convos with someone where you end up talking for a long time and you're not even that close. My last memory of him is him arguing to hand in his answer sheet and sign out after our structural design exam on Monday. And today. . .he's gone. Forever. I seriously don't know how to feel. What to do. I can't fall asleep. I'm almost scared. I've been suicidal for a long time. He knew. I remember him telling me that its selfish to want to die. Its almost like he knew. But he didn't. What if it had been me? How would the situation be right now if I were the one that died? I'm going to be up until nature forces my body to fall asleep. Because the thoughts running through my mind right now are just too much for me to handle. Way too much