In a couple of books that were written before Cullens and AMR, I think Columbine a True Crime Story and Far from the Trees go into Sue's past with anxiety and fear of death. So Pixie you're right, it could have been postpartum depression, she may have been more susceptible to it?
It could have been a worry about the baby's health and when he was diagnosed with pyloric stenosis she may have forgotten about it after then when she was writing the book she could have remembered. Or it could be a hindsight thing.
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"And you know, you know, you know, this can be beautiful, you say you're numb inside, but I can't agree. So the world's unfair, keep it locked out there. In here it's beautiful."