I know religion is not something one is supposed to write about on HN, but this is a personal help issue and not a technical/social discussion, so I hope I will be forgiven.

But seriously: my advice to you is to find a pastor/cleric you can trust and talk to him about your situation (many are in fact trained grief counselors). I too lost a good friend some years back, and my faith and my relationship to God were really what brought me through the time of mourning. Please at least consider it.