Im at a loss for what to do ..

My boyfriend has an ex who together the have a daughter beautiful little 3 year old , his ex is normally pretty cool most of time and everyone gets along well yesterday my boyfriend told his ex he has a possible job opportunity up north with good pay so he can support his little girl and us , well he left this morning for his interview not even 3 hrs after i get a text message from his ex asking to change their daughters last name from his to hers and all this junk and then at the end throws in a "And good luck tomorrow ☺" needless to say im shocked i dont even know how to bring this up to him i dont want him upset thinking hes gonna loose his little girl because thats what she does and shes done this to him before when they were together i really need advice on how to approch my boyfriend with this new info because i dont know how ......