Or maybe taking a personal music player for yourself and listening to soothing music or meditative cds-- would help at home,too, while she's there. (If the girl sees you're wearing earphones, maybe she'll realize she can't talk over that.)

I'm not kidding; her behavior can be very disruptive of mental processing. Just excuse
yourself from her presence if necessary, imho.

I feel sorry for the son whose girlfriend she is. She has an ego problem not to be able
to control it for others' sake.