I agree that you shouldn't be asking your dd now. She has told you how she feels. You having a single chat with him is not going to change her feelings.
She will feel obliged to try and get on with him for your sake. Do you know that children often feel that a relationship breakdown is their fault. 'If only I had tried harder to be good, to please him. If only I had been quieter, or cleverer, or prettier, then they would still be together and mummy would be happy'.
She will say and do anything if she thinks it is what you want. Don't ask for her opinion. Take control. Be the adult and remove her from this environment so that she can grow up emotionally strong and confident that her needs are just as important as anyone else's.
Don't allow her to grow up thinking this, it will only send her into the arms of a man who can emotionally and abuse her.
You know he won't change. He's had 6 years to change, tell you about his 'medical condition', seek help. He's done nothing.
He has treated you so awfully and the fact that he thinks he is done now, he has said his bit and now the The Great Man has spoken, everything can get back to normal, tells you what sort of man he is.
Where are his actions? If you left him, do you think he would come running after you. I don't. If it's not handed to him on a plate, he's not interested. He will find someone else to run around after him and try, in vain, to please him.