How do I help my dad through my mother's passing?

My mother passed away this week. My mother and father had been married for 26 years. I am their oldest son of 7 and so I'm pretty devastated as well. I'm extremely exhausted and depressed. I feel that my dad is going through worse though, thankfully, he doesn't drink or smoke, so he's safely grieving. I still feel enormous pain for him because I can only imagine the loss he feels, so what can I do to help him through it?