To add to NYs excellent post--my S17 hates my H as well. My D21 tolerates him. Neither has really cared much for him, but my S really hates him after he had an A and left me. My S is angry that H hurt me so much. He was really angry when I let H come back. He is my child and he is protective of me. I've tried to talk to him about forgiveness and how humans make mistakes and that he may go through some of these same trials later in his life. Nothing helps--he refuses to forgive. I understand why he hates H.
Something that my C told me once--someday the kids will be off having their own life. This is my life and these are my choices. Whether they are good choices for me probably remains to be seen, but I am an adult and can make the choices. Someday they will see that even though S will probably always hate H.
I'm really sad about it, but I've accepted it. My S doesn't understand that I contributed to problems in our M--I'm his mom and I didn't do anything wrong.
So your D may always feel this way about your H too. It is your life and your choice to make. It's easy to be influenced by others. I've found that I am avoiding people who have negative things to say about my H (not my kids, of course). I'm easily influenced cuz I'm insecure. I'm not always confident that I'm making a good decision.