But I do have something to tell you.My mother died a short time ago. She wasn't feeling well for a couple of days and told my brother not to come over and see her - she had the flu and she didn't want him or the grandkids to catch it.
Well, she died suddenly on the third day. My brother thinks it's his fault. Had he gone over (even though they talked on the phone at least 6 times over the two days) he could have done something. But he couldn't - my mother didn't know she was deathly ill, and she wouldn't have gone to a doctor for the flu. In the end, he could not have made any difference.
And in the end, you couldn't have made any difference either. It's not your fault. Feel bad, but don't feel guilty - I've seen how that can really do damage to you and the people around you.
Go be with his family and remember him together. It's the best thing you can do for each other now.