I would have thought that meant the baby died as a result of her death, but the wording makes it sound like she died as a result of the baby's death, which is gruesome on a whole other level.
I imagine that life was just not working out as he intended so he decided to start over. These guys do not see other people as important or existing outside of his own perception. Other people, even their children, are accoutrements to his image and when he is ready for something else, he gets them out of the way and on to the next thing.
I co-parent with one. I was lucky to have been given the chance to get out with my daughter under the oversight of the law and the courts while he was in jail. My exes' goal is to ruin me and take full custody, and as long as I prevent that, he continues to compete in the better parent game, which keeps my child as safe as she can be while she is with him, because his image of being as good of a parent as me is important to him as long as I am in the picture. And he knows I will go legal on him at any mis-step.
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