Headcanon - I honestly believe this is what Rose saw during her brief moment when she was the Bad Wolf. She could see every possible alternate reality, every possible timeline and every single one of them was real. They were all happening off in some other universe and she could see them all at once. Some were happening in the past, some in the future, some in the present and most surprising was her having a family of her own. What made it so heartbreaking for her was that this was the one universe where everything turned out wrong and she was the one version of herself who wouldn’t get a happy ending. So along with the physical pain came a deep emotional pain over this epic revelation.