1 scenary:her husband is a piece of crap and she decided to leave with her daughter, in that case she is still a piece of crap too, not just she broke up with him to marry a bastard, but she also decided to escape to her his house and probaly will bring trouble to him.
2 scenary:her husband is actually Nice and their house just got destroyed for some reason, and now hes finding a new one, in that case shes still a piece of crap, she could have gone to any other house(woman friend, her parents house, apartment...) but she decided to go live in her ex house(probaly behind his back), when her ex live alone and inst married, this is Just disrespectful, both to the ex and principally to her husband.
I simply cant see this manga giving a good explanation to this situation, literally even in scenarys like "her husband died" or "she was forced to marry him", i simply cant see this with good eyes she just spawning out of nowhere in his house and appearing with a daughter, i can understand the MC letting her live in there for some time because its the "responsability" of adults to take care of the children(by law is the father or guardian of the children, and we are not responsible for others people children, but If a mother and child apper needing a house to live for some days, unless i absolutely hated the mother, or thought that It could be dangerous to let them live with me or i was married/lived with someone else i would too let them live in the house for a few days, the kid dont have fault in whathever happened between the mother and MC and i would hate to be in that kid shoes and having to look for a house for days), but both not doing any shores and making the MC do everything is simple wrong(shes at least 30, and behave more like a child than her own child), and the scenary of her husband being actually a good person make this all even worse, literally a wife living inside her ex house, and sometimes even being alone in the house with him when her daughter go to school, this manga will need a really good excuse for all that, and even then It will look bad.