Our expert says:
I don't understand - she is his NIECE, no his daughter -why is he so desperate to inflict her on you ?
Anyhow, if the brat is with you and misbehaves, you are entirely free to discipline her, at least verbally, and to expect her to obey and behave or go home.
But the extent of his devotion to this litle girl sounds way out of normal proportions, and seems more important to him than his relationship with you, which is really odd.
Either consider this relationship doomed, or get him with you into couples counselling
The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal
advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.