You are contacting your W less and less. Right now it seems she is very set on selling the house and since you both own the house it is something you will need to work on together (to a point). Of course she will throw in a nice comment here and there as she senses you are slipping away and right now, until the house sells she needs you to be "on call" with her questions and concerns.
I would keep the e-mail very business like as others have suggested. And very good job on waiting a few days to respond. Not all queries from a WAS require an immediate response or a response at all. If she continues to try and make small talk I would let her for some time to come before you engage in anything other than business exchanges. If the small talk only is accompanied by house questions or other administrative tasks you will have your answer. If she begins to reach out in other ways then perhaps you can reciprocate.
