I, personally, wouldn't be talking to him about selling the house right now, if that's not what you want to do. In fact, why even sell it until you are ordered by a judge to do so? You and your son still have to live somewhere and why not remain in the home until after the divorce? In my case, I was given 3 months to either buy him out or sell the house once the divorce was finalized. It's your call, but I wouldn't let him drive the bus on YOUR decision about YOUR living space at the moment.
I would also limit the number of invitations that you give him to spend time w/you and your son. You currently have been fired as his wife, so why make it easy for him to play a "family man" right now? It's time he started spending time w/his son on his own a bit more and this will allow you time to do things for yourself. Let me ask you this, if you are divorced, are you still going to invite him along on activities w/you and your son?
Are you responding to all of the texts he's sending you? If so, stop responding back so readily. He knows what time you pick up on your son at day care, so that is a no brainer. As for inquiring about how his son is doing, I would set a time in the evening for your son to speak to his father and encourage him to do this. Again, you aren't obligated to respond back to his calls/texts asap. You are busy w/your life, taking care of your son and the home. In his PA way, he's checking up on you to see what you are doing (just my two cents).
Time to try something different. He needs to realize what a divorce will look like, i.e., you moving forward and on w/your life and not at his beck and call.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
