J - I can only speak from my own experience, but the level of communication I had depended on the level I needed to heal. Whilst my emotions were still at the mercy of his behaviour / mood swings, then it was best for me to keep it polite, but to the bare minimum. If I did this, then there was less for me to analyse and dissect and less for me to get hurt or angry about. I could not heal if all my thoughts were about him, about what he meant when he said 'I'll see you later tonight" or "I'll drop the children off at ...". At first, detachment is something you do (you force yourself to do it because every fibre of your being is working against detaching) but eventually. LH is right, it is something you become.
Once I was no longer affected by him, then I relaxed my stance. We have moved beyond the "yes", "no" and no response to informational texts. Ours are polite and well meaning but not lengthy or funny. Casual acquaintances - the neighbour you don't really know but say hello to if you run into them.
I think your response was fine. Be careful detachment doesn't turn into rudeness. If you ran into your neighbour in the store, you'd say hello, make small talk and then merrily go on your way and not give it another thought. For me, that is detachment.
