I'm not sure what to say in reply- there's a lot here and in the previous post.
Mary Todd Lincoln was not ' mad ', she was and remains one of the most tragic figures in history. She was, however, vilified, slandered, victimized, bullied and attacked. Assertions on her and a supposedly fractured marriage are just not based in fact. Between marrying the enemy-est enemy of them all, for which her Southern family ( and the elite Southern society in which she grew up ) never forgave her, she was attacked by those too chicken to attack her husband and managed to pick up what amounted to a stalker, an ex-law partner of Lincoln's ( Herndon, although hate to give him a name ) on the way.
Because something is written down and worse, published does not make it true- Herndon's ridiculous book is sourced into 2018. Earlier books sourced back to Herndon get sourced, and it continues. But no one looks into Herndon's motives and sources. Guy made a fortune on writing shock-horror dreck about her and more touring the country. He filled lecture halls, selling tickets, as some ' expert ' on Mary Todd Lincoln. We do love hearing awful things about someone, the more famous, the better.
There are quite a few threads on Mary, so will not engage in an argument about her. The thing is, when incorrect information on her comes up, it has to be addressed or she is still fodder.