Fake a headache. While it doens't let the hostess on to the truth that it is her behavior that has made you want to leave, it will work none the less.
Of course, if your goal is to subtly alert the hostess that her behavior is what has turned you away, this becomes more difficult to relay. Perhaps just say "thank you for inviting us, but I think I am ready to go home now" and simply leave it at that. Your abruptness should give her a hint and if it does not, I would not worry about it because I'm guessing you are going to try to refrain from visiting this woman again in the future anyways.
ETA: I just noticed your name is "migraine milly." I didn't notice that when I told you to fake a headache! Perhaps you won't even have to fake it, huh.