I haven't yet taken the time to read the three pages of comments on this story, so forgive me if I repeat what has surely been said. This was beautiful and satisfying, in the way only something so completely bittersweet can be. The genre stated EWE, but truly, this was epilogue compliant, as far as canon tells us. Harry did marry Ginny and have three children, Snape did die in the war...but did Harry "wish" him alive again (consciously or not)? He certainly seemed to be back *for* Harry, to fill the spaces Ginny no longer occupied.
Writing with borrowed characters/backstory is tricky enough, but merging them into another story's framework is risky business. You did this brilliantly, with no silly contrivances (other than Ginny's hilarious merry-widow get-up). I loved it! Well done!