Earlier quoted context omitted.
I apologize in advance if this question is intrusive but is there any possibility it could have been an accident? Sometimes the line can be blurry. Accidental suicides do happen. Especially since there was no note.
Unfortunately, the way I found him pretty much rules that out. I'm foregoing description to be kind to family and friends, but it wasn't something you accidently do. A couple minor things he did directly beforehand which would seem completely innocuous to everybody but me also gives me confidence in the conclusion.
I didn't realize until seeing this that you were the person who found him. Please don't be afraid to seek counselling if you have flashbacks / nightmares / difficulty sleeping / etc -- post-traumatic stress disorder is very commonly experienced by those who find suicide victims.