The others here have already said pretty much what I want to tell you. When my brother died, I was in a state of shock for a very long time. It was hard to accept that he was gone, and even harder that it was by his own hand. Everyone grieves in their own way. Some need to talk about it, while others draw within themselves. Just stay close to your friend, and let him know he can talk to you if he needs to, but don’t push him to talk about it until he is ready.
The difficult thing for me was wondering why, and trying to understand what was in my brother’s head when he pulled the trigger. then I wondered what I could have done to stop it. it took years for me to finally understand that there are some answers I will never have.
I was lucky enough to have a good friend be there with and for me throughout all of this. Sometimes, just having him sit quietly by my side was enough. There are no words you can say that will stop his grief now, but he will look back and appreciate your efforts over time. I’m so sorry for his loss, but he has a good friend in you.