Short background bit - DD is 15 and lives with me. Her dad moved in with the woman he was having an affair with 3 years ago which made DD very angry with him. Their relationship has slowly improved over time and she now spends every other Saturday night & half of Sunday with them.
As she's a busy teenager she plans stuff for the other weekends and when he changed the weekend he could have her because of work commitments it clashed with an important event for her. She called him to say she understood it's not his fault but this event was booked before he changed the weekends and before she even finished explaining he was shouting and swearing at her (she was on speaker so I heard the whole thing).
She was quite calm and told him that he shouldn't be shouting and swearing at her for something which isn't anyone's fault and told him she was going to end the conversation if he didn't stop. He did calm down a bit but went on about how it wasn't fair on him. She patiently let him rant on a bit more and they sorted an alternative date and she told him off again for how he shouted and swore at her. He then ended the call and the poor girl burst into tears of anger.
I think she handled the whole thing incredibly well and maturely (unlike her dad) and told me I didn't need to get involved but I just feel that if anyone else treated her like that I'd rip them to bits so should it be any different for her dad? I know she'll be fine when she's there as she's very close with his girlfriend who will look out for DD (she's already texted to apologise for her dad's behaviour).
WWYD? Respect DD's wishes and stay out of it? Or say something? If so what?