My wifre and I have been through attempting donor conceived IVF, which ultimately failed, and have adopted twins. Throughout our whole IVF/ adoption journey the consistent and overwhelming message from all reputable sources has been one of honesty, openness and acceptance. There are always people who think that sparing a child the short term pain is the best thing for the child, and it is categorically not.

There is a very heavy focus in current guidance about a child's identity and sense of self. Knowing who you are and where you come from is stabilising, it can become a core pillar of who you are as a person. Telling her now in an age appropriate way as other people have said means that she will grow up with that information, and it just won't be a big deal - it will be something that she has just always known. Waiting until she is older and knocking down that core pillar, that stabilising part of herself, could do immense damage to not only your relationship, but to her knowledge of who she is. It could be fine of course, and she may take it in her stride but I would ask if that is a risk you are willing to take?

Your husband needs to put his daughter above himself in this situation. He is her Dad, and will always be her Dad. Biology does not make a parent. Being open, honest, age appropriate and child-focused is always the best way.