That's a tough one man, my sympathies. Just keep telling yourself he's in a better place, and know that all the pain/problems/worries/stress he had while here, are all gone now. He's the happiest he's ever been... RIGHT NOW!
Also know that you will see him again- just like he's now seeing his parents, for the 1st time in a long time. And I know you have to be happy for that. =)

But nonetheless, it'll be tough for a while. We're all with you and will share the pain with you. If you need to talk, hit me up anytime. My heart's always open and ears ready my friend.