LW1 - I've seen children treat their parents with disrespect like this and it makes me sick.  Best thing was to snip this in the bud when it started, which was probably in her very early teens.  If that's the case here, then the parents avoided being parents while this monster of a kid fermented in a petri dish and now the parents have to deal with it on this level. The dad should absolutely step in if the mom can't handle confrontation. That's not sexism, it's sharing of parental roles and many times the man can handle confrontation better than the mom. Sounds like dad is staying on the sidelines, which is BS. Since the problem is now embedded in the relationship, it's time for a coming to jesus moment with the daughter and set up the ground rules from today forward.  IF the daughter can't handle it, out the door she goes and she can talk to everyone else that way and find out how that works in real life. And dad needs to grow a pair and get engaged.