@Smileless yes there hasn't been a formal estrangement as such, as in he has not said he does not want anything to do with us. I suppose if he actually says he wants nothing to do with us, that will be the cut off point and I'll accept it more.
To others on the post who may not know, his behavior became hostile and aggressive while we were delivering his stuff to his new home, so we left- and he has not answered messages since. He is also unhappy because we forced them to move out as they were not intending to. We had originally agreed a stay of three months, but it turned into 7. We really enjoyed the time with our Grandchild, but felt he deserved better than the three of them squashed into our box room- and we hoped our son's (hostile to us) behaviour would improve if they had their own space.
I don't really know how to go about trying to contact him after this time, so any suggestions are most welcome. Please bear in mind that I am a "bad mother" and he has already said he will never respect me because I am divorced." He thinks I denied him a relationship with his father because I am divorced. (!!!) None of this is true, but he cannot see that his father did not ever make time for him before or after the divorce. If there was a bond there, the divorce would not have broken it. Unfortunately his Father only has eyes for one of his children and it's not him, so he lashes out at me. There may be more reasons I don't know about.