[H] OT: Who wrote this story and what's the title?

[Steve Tomporowski]

This is way off topic, but one of you might know the story I'm talking 
about.

My buddy down in Florida is corresponding with a 96 year old former B29 
aircraft commander and he mentioned a story, which he said was by Mark 
Twain (I tried to find, could not) about a person that lost a 
loved-one.  In response to his prayers, an angel came down to show him 
what would have happened in the future if that one had lived and 
basically, it was a terrible outcome, so it was better that that person 
died early.

Now the potential for satire is there and it sounds like something 
Clemens would have done, but I've run through his novels and short 
stories and found nothing even close.

Any ideas?  I know it sound a lot like 'It's a Wonderful Life', but it 
should predate it....

Thanks....Steve