Erm.. she stay for dinner why exactly?
Can anyone explain why you even think about accepting a dinner invitation from someone you know to be a violent drunk, indeed someone you have personally reported to the police for beating his wife?
So what, to make up for reporting him to the police she does the washing up? Presumably hoping to not only get some free food from a wife-beater, but to avoid a beating herself by cleaning up afterwards..
And after arriving, finding that she was (sort of) alone in the house with this guy, she still stays to have dinner with him? She couldn't think of any excuse for getting the hell out of there as soon as she realised his wife and kid wouldn't be joining them? Yes I know she found out they were dead later, but wouldn't having dinner alone with a psycho be enough of a reason to want to leave?.
The more I think about this, the more I wonder if she had a death wish. I don't even want to think about the possibility she was considering getting romantically involved with a supposed recent divorcee with a track record of violently beating his spouse.
The guy's actions in inviting someone that shopped him to the police are more easily explained. Except that he apparently didn't get time to off her too, as she made her escape after finding next week's dinner party in the freezer.
I hate to say this, but if anyone deserved a good slap round the head for being a muppet, it's someone that stays for a candle lit dinner with a violent psychopath - and then does the washing up afterwards.