I read something about this not long ago but it wasn't a wiki. Very interesting stuff. Had no idea.
I think what I read was a chapter out of this, when it was released. I think it ran in Vanity Fair or something. https://www.amazon.com/Your-Friend-Forever-Lincoln-Friendship-ebook/dp/B01EB74DE6
Not sure if the author says they consummated a sexual relationship though.