Oh, I am sorry for dd and for you, must be dreadful to see him hurting her. My parents divorced so I feel for dd, I was very anxious about whether daddy still loved me (fortunately we have a good relationship as adults but will never forget that insecurity).
Your ex sounds like a selfish tosser, btw, someone who lets his daughter down because he doesn't want to stay in when she's ill is not fit to be a dad, really. She'll see through him one day, if not now. And all you can do is love her and not slag him off, however unbearably tempting it is.