If this story is real it sounds like the pregnancy could have caused psychosis it's pretty common or bi polar

It's very likely left alone with no interaction this worsened

I have another theory but you read more than me I think she was just lost her mind after her son died and I think she could have heard his voice tormenting her or her vision of it

I don't think she killed him I think he just died she blamed her self any parent would this manfested as sicizophrina with visual or auditory that untreated she got paranoia and retreated in to her own world.

I do agree there's nothing to be gained by exposing this other then hurting the child's father