Bellatrix had a heart deep down hidden which is why she told no one when she was pregnant. She used glamor charms to hide. Not because she was afraid her husband would not want it. But because it was not his child. She would be killed if they knew. It was a moment of weakness on both parties. Her and a Blood-traitor not just any a Half-breed at that. With a twist Lily is not in this book and you'll understand when I finish this book because then I'm going to be putting up the prequel. Obviously most of the time the Prequel comes after the first book or movie.