In my opinion, you SIL was nothing but rude. She's the one who's outta line. Not you! I'd have done the same thing. They wouldn't be visiting me until the SIL learned some manners. Good Lord, what a jerk she is. I wouldn't worry about looking like the bad guy, because you did what's right. They can either get over it and realize the SIL messed up.... or just stay away. I say, Good for you!