D and D

I know a lot about Narcisists now that I have educated myself, due to my previous relationship/divorce from a Narcisist. I have experienced D and D and didnt really know what that was called until I came to this site.
I have LC with my ex (after a brief consideration of reconsiling with him several months ago). I do not contact him about anything except D and over the past few months always just answer his requests and dont attempt to engage him or ever contact him. More recently our communications are re: visits or him wanting to talk to her. Because I am her mother (and I am way past thinking I can share in the delights and daily growths/experiences of my daughter with him), but once in awhile I will respond to his text and tell him something about her, as in, she went to camp today, she is ill, she is getting a phone so you can talk to her more, I emailed about her health insurance as it is changing and he needed to know some facts about it because he may have to pay some towards it soon (I know you may see that as engaging and perhaps it is-I am open to looking at this and making changes). But now HE doesnt respond to me. It almost feels like he is now NC. I realize that some divorced people can co parent with this type of communication about their children and some are even friendly-not that I want this with ex or even think its possible with narc. Is this part of D and D, they just flat out ignore you? Or is he establishing whatever boundaries he is insisting on.
I know its business only and I suppose I need to tighten it up even more.
Again, I am still blown away tat 6 weeks ago he was professing his love and now D and D. I know, as Abreva says, I am not surprised but it is a difficult thing to process, because it is INSANE that someone does this.