This guy broke mistress Bastienne's heart and she did not want to suffer alone. She wanted him to also feel what she felt even though it would not be the exact same feeling. She wanted him to feel something and that is why she opted to facesit him and to feed him her poo. He learned his lesson the hard way bit it was too late as she did not want him back.
Mistress Bastienne wanted to show her boss that she did not like what he had done. He was not fair on her and he made her life miserable. She was so pissed at the toxic work environment and she had to punish him. The mistress cruelly made him eat her shit and drink her pee. He told her he would change but she knew he would victimize her. So she quit after she was done humiliating him.
Mistress Bastienne was humiliated by this guy and she had to get even. She made sure that she got what she wanted by turning the guy into a human toilet and forcing him to eat her shit as well as drink her pee. It was brutal but she did not care as she felt that he deserved it. She then chased him away after he had cleaned up her house.
Mistress Bastienne did not have butter in her house but she wanted her slave to use something else in its place. She knew he was fond of butter so she made him eat her shit by spreading it on his bread like butter. He was shocked at what she asked him to do but when he realized she was dead serious, he did what the mistress ordered him to do.