Hey Dan, at the beginning of your thread you suspected a MLC. Has there ever been any sign of an OM? If not, I'd say you have to get rid of any negative feelings and then try to establish a friendship with your W. Whether you engage in small talk or not would depend on where you two are at.
If the chit chat just fuels tension, I'd avoid it. If the negative feelings are fading, I'd try to leverage it into a friendship. Of course if there's an OM in the picture, that's a whole other story.