HAW
I am so sorry that your family is going through this.
I do hope that you keep posting on MN, even though some of the posters have been quite harsh. It is a very emotive subject, particularly if the poster has personal experience of abuse.
IMO (and I have no personal experience) your daughter obviously needs to know that you are there for her, that you believe her.
At the same time, I don't feel that it is terrible to show her that you are shocked and that you cannot believe that your husband would do this. (which is not to say that she is lying, just that you would not have thought he was the kind of man to do this)
Of course you find it difficult to believe that he would do such a thing. It would be terrible if your daughter had said that she was being abused and you had thought, "Oh, well I can believe that of him, he always was a bit funny with her"
You would not be in a relationship with him if you thought for a second that he could be a paedophile.
You sound like a very loving and caring mother who has had the rug pulled out from under her. Sometimes just by posting on MN it is possible to sort out ones feelings and get a clearer picture. I hope that this is the case for you.