Dolfin,
I am so very sorry to hear about your friend and co-worker Reinhard.
Having worked with Hospice and grief counseling, one thing I can offer is that grief is very real and *necessary* to the healing process of the grieving person. Unfortunately, our western society can't deal with death well, so we sweep it under the rug and get 3 days off work. However, grieving (depending on lots of varying circumstances) can be from 1-3 years.
Grieving is healthy, hurts like anything at first. But those who don't grieve appropriately will either grieve years down the road or the grief may come out in physical illness.
So, please be gentle with yourself. Allow yourself to grieve. If you would like to talk, please feel free to PM me anytime.