Grief takes time to pass and the scars to heal.
I lost both my parents before the age of 15. I'm 19 now, and I still cry over the mistakes I made before they passed, and how I wish I'd tried to spend more time with them, even though they were abusive assholes. They were my parents, and loss hurts.

Be there for him by literally just being there. Tell him you love him, be nice to him, if he needs help, help him. That's the best thing you could do for him.