Could you tell me how to grieve (detail inside)

Ok so this may sound stupid but I need a little help. We’ve just lost a great jelly, who also happened to be one of my best friends. I didn’t see that coming and our friendship was still there, so the loss has caused me a lot of grief.

The thing is, I want to get over this feeling quickly, I still have a lot to do ahead. But the more I try to suppress it, the stronger it becomes. I haven’t got back to my right mind yet. Am I too obsessive? Could you tell me how I can get over it?