It's been almost 3 years since I last posted this thread, but until now I'm still looking for this novel. I finished reading a lot of novels since then but I still can't forget this one. These are the details that I can remember: * MC: transmigrator, she knows martial arts, beautiful, she rarely goes out, and when she's out in the public she covers her face that's why people think she's ugly. I think she has a weak body that's why in the later chapers she would exercise in her courtyard. When the engagement was broken, people pitied her because they think that no one will want her anymore. And as a compensation, the imperial family gave her lots of money. And I think she was given a title of a princess despite not getting married with the prince. * ML: a prince from a neighboring country. She has a sister that I think has a relationship with MC's ex-fiancé.(?) * Ex-fiancé Prince: the reason why he wanted to break his engagement with MC is because of the rumor that she's ugly and he has someone that he likes(?) * MC's Mother: deceased, related with the empress(?) * MC's Father: has something to do with either politics or military. he loves MC and dotes on her. * MC's Stepmother: she's not an evil stepmother. she really loves MC like her own. * MC's Elder Brother: has something to do with either politics or military, his wife is from an imperial family *Ex-fiancé Brother: he lives in a different town and when he found out that MC broke her engagement with the Prince, he hurried back to make the MC her wife or concubine. He already has a wife and concubine. He has a disease that was cured by his wife. *Ex-fiancé Brother's Wife: she was also a transmigrator. MC and her knows each other in their world. In this ancient time, they met in a banquet. They hang out and such. She knows medicine and has a famous clinic. * MC's Female friend: she's fat because her family spoiled her. She has a big family, her father has a lot of concubines and sons and all of them genuinely likes her. She's engaged with one of the prince (MC's ex-fiancé another brother). That prince also likes her genuinely. When she became friends with MC, I think she temporarily lives in MC's manor to exercise to help her lose weight. That's all I can remember about the novel. I hope you can help me. Thank you.
The only one I remember that somewhat fit your description is Demon Wangs Golden Favorite Fei. Don't remember too much about this one though. But I remember MC being from an important descent on mothers side, knowing martial arts, weiring a veil and being considered ugly, having her engagement broken and ex turning to her sister. However as far as I remember father or stepmother didn't treat her well in this novel.