@Elless so glad you can continue to communicate with your GCs. We had a similiar situation to you inasmuch as we had a fraught relationship with our daughter which led to an initial short term estrangement then we were 'allowed' to see both herself and the GCs again, I wouldn't dignify this situation by calling it a reconciliation, she was constantly finding fault, everything we said or did was wrong and in the end we were so reduced as people that we just took whatever she said in order to be able to see the GCs, but when she started to abuse us online we knew it was game over. But the treading on eggshells - oh my God - that was a regular dance for us and it exhausted us. So I understand what you are saying about having a weight lifted, it didn't feel like that at the time when we were cut off for questionning her online abuse, but after a few years when I woke up without crippling anxiety and dread but a feeling of calm, I knew at that point that living without my daughter, whom I loved and do continue to love despite everything, is so much better for my mental and physical wellbeing than living with her, and for that reason I do not see, after 11 years, that a reconciliation will be on the cards, because the injury she could still inflict upon us, at a much older and more vulnerable age, does not bear thinking about.
But for you perhaps there will be a time when your son once more reconciles with you, however, if he does make sure it is on both your terms for your own wellbeing.
Wishing you all the best xx