You might want to remind your D that you loved and accepted her when she went through her awful teen years. Or some unloving behaviors she exhibited at various times over the years. You did not shut out or reject D because of her awful behaviors in the past. Tell D that this is what you are doing with W and their mother. Show her what unconditional love looks like and show D how a proper H acts/behaves. For you are D's role model of a man and husband. D is watching you and taking mental notes.
Monkey see, monkey do.
Did your W experience trauma or any life-changing events prior to BD? I am curious to learn more about W's trajectory from a W/mother to a person who engages in an A with the OW after 25-years of marriage.