Fight, I struggle too with the whole indifference vs. anger. Mine feels a tremendous amount of anger at me. Great vats of steaming, bubbling, toxic rage. Is that good? Does that mean he still cares? If so, I wish he didn't. I think indifference would feel so nice.
Narcissists crave CONTROL over all else. Mine controls me by not letting me talk. We will talk, as we did, this weekend. Then he tells me he is done talking and won't respond to me until the next day. Then I don't respond to him, yada yada yada yada. How do I get out of that game? How do you?
Do you really think talking to him is going to resolve anything on the custody or spousal support issue? I think not. I think it will just keep that simmering vat boiling over. I would tell him straight up that the lawyers will handle this. In the end it will be cheaper and save your sanity. My friend finally convinced me to stop talking to him about anything other than the kids and tell him anything else has to go through lawyers. I finally feel better. I set my ring tone to silent, my text tone to silent, and no vibration from him. I won't panic one more time when I hear one of those tones.
You have your plan. Keep things calm. Get out of the house. When you get down the road a little, work through lawyers to put a close on this.
Once you aren't in the same house and don't have to listen to him contradict you on a T-shirt image or imply that you are a horrible parent because god forbid your child could have ingested one fish oil capsule, your life will change to such an extent and you will be able to breathe in a way you haven't in your marriage.
You are getting closer my friend. Your freedom awaits. Lest you question your actions (and remember he put all this in motion) I will say that the further I've gotten from this, I see that my children are treating me in some ways as he always has. I'm shutting that down cold. You don't want your son to grow up like him. That simple.