The story you are looking for has been taken down. I guess they are never gonna finish it.

I knew it was this author. I went on wayback and found a link that works to the author page but not the story.
Incandescent by Darkrivertempest
All Human/AU. In 1838, a financially bankrupt Elizabeth Summers agrees to bear a child for an anonymous English landowner, in exchange for payment of her father's debts. But eight years later, after giving up her son as agreed, Elizabeth is unwittingly hired by the Englishman's sister-in-law Drusilla, to be her own son's governess. Will the anonymous Englishman, William Goodwin, rekindle the deep passion he and Elizabeth once shared or will he dismiss her without a second thought?
Maybe someone has a copy of what was written.
It was the start of a good story. From what I remember didn't even get to Buffy even being pregnant yet.