It is the 16th 17th century setting. A mother marries her daughter off to a man she is not happy with. He is well known and respected and possibly public figures. She falls in love and bed another man and gets pregnant and ends up having to give the baby to the fathers family. She is sent away during her pregnancy at which she had also moved her friend into their home and her husband beds with her friend and moves her children in with them.

Maybe " the duchess"