Pandaemonium
While we're never shown Lahabrea actually doing the deed, the fact Athena was said to have met with an untimely death in the Asphodelos story and what we're shown here heavily implies that he did kill his wife. He intended to do so, as during / after their soul fusion he was so horrified by her sociopathy and lack of concern for the Star™ he split the part of himself that had been "infected" by her during the soul merge into Hephaistos.
Agdistis suggests he still knows everything that happened, and he's just so ashamed about it and trying so earnestly to protect Erichthonios from the truth about Athena (whom he loved dearly since her sociopathy wasn't clear to him) he's kept the memory to himself. Hephaistos is, for all intents and purposes, who he could have become had he not removed that merged part of his soul from himself. He still knows everything, he's just not moved to act on Athena's infectious (for want of a better term) desires.
'course, this is only the second tier, and the Lahabrea we knew was a lot closer to Hephaistos in personality than the austere man we met in Abyssos... and given the Mateus parallels I'll hardly be surprised if even "good" Lahabrea winds up being not so good in the end.
The Tataru stuff is nice, but it's really just fluff unless you're hankering to spend 20k gil on portraits of the Scions circa Endwalker. The post-MSQ stuff is cool though, it explains Scarmiglione and Barbariccia's backstories as both mortals and Voidsent. Nice way to include character detail without slowing down the pacing of the story.