Heather, Your STBXH was probably having a wee moment of clarity and was actually thinking about his family. Words are just that words and they do love to draw us into their drama and once we are back in and drop our guard, they hit us again w/a loud BAM! I had another thought about him his words today...could it be that he's just now starting to realize that the divorce will make everything final and you will finally move on w/your life and possibly find someone new? There are any number of reasons for his niceness...but I wouldn't let my guard down.
I do agree w/Bea and Bright...I wouldn't carry the conversation on any further.
Keep moving forward.
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.