To put it simply, Jon needs to step up and deal with this. It was easy for him to turn a blind eye before, but he's seen it now and you've called out the behaviour so he's aware its a problem to you. He also should have put her straight when she was being unkind at the dinner you hosted - she went on about an orgy and hand fed him?!?!

I have a feeling he's not going to do much about it.