Woman is losing husband.Gets in crash. Dreams she is walking away but is really in coma... dreams she is in cabin with boy and his father.Talks to boy... Father thinks she is imaginary. She falls in love with both... wakes from coma to discover that boy and father are real.

I hope someone answers this question because the story sounds really good and I'd love to read it! Reminds me of the book What Dreams May Come by Richard Matheson except in that book the man dies (Robin Williams played him in the movie) but at first thinks he's dreaming. You might like Somewhere in Time also by Richard Matheson - Christopher Reeve was in the movie - about a man who tries to go back in time since he fell in love with a woman from a different time.