I don’t know if my response helps.
As Mutt said, your son is in grieve. His world collapsed, everything he was certain of, vanished. Anger and although he knows divorce is final, still, deep inside he hopes to see his parents together. It won’t happen, he knows.
Kids, although said otherwise, aren’t resilient as may want us to believe or argument. It is a justification for one of the parents own distress, a deflecting argument (it is better for the kids, etc.)
Kids coop with the fact, make the best out of it, falls back into grieve. Now, still with open wounds, it is common that kids fall into ‘extreme’ behaviour, drop out at school, starting to drink, exploring ‘other’ friends, etc.
They face consequences for life. With graduations, marriages, birthdays and family gatherings. Not to mention that they divorce a 50% more than others, so there is emotional damage in trusting and sustaining a r/s.
Another part. You know the old family dynamics. What was your son / kids like?
Was dad (ex) because of his behaviour more pleased by the kids, that they avoiding upheaval, tried to be the good boys (pleasing?)
How did dad influence the kids, specially the 18 yr old, the receptive one?
Normally (reading all the stories and knowing something about Cluster B) and as I experienced, the ‘BPD-parent” shows manipulative behaviour. Not directly, very subtile.
Making kids feel obliged (even guilty) when something asked. As to consider how the BPD will feel when the kids doesn’t agree, doesn’t want to help, doesn’t want to do something.
Like:
ever thought about it how it would make you feel when you ask me xyz and my answer is no? Did you ever?
In other words were they (special the 18yr old) smoothening in order to stabilise life for themselves and family?
Were you the parent that was ‘always’ there, comforting them, hugging them, also the one that had to set boundaries, played, helped with homework; the one to rely on, no matter what? Were you?
Having said that, towards kids:
Nice words are so powerful, are so full of magic… Experienced it.
Your ex is now desperately trying to keep the attachment with son alive, with all means.
The manipulation, as I mentioned, will be used with all means available. Now to paint you black.
Manipulation in order to test and steering the wheel to drive into that loyalty conflict.
He, dad, is so damaging his own son, sadly he is not even aware of doing so.
Towards you, mom, the stable partner, kids came for a kiss, a hug, were able to show anger, discontent, honesty and telling their ‘little secrets’.
In fact he (son) still does, but is now able to show his full anger to the stable mom.
Talk and talk with your son, please.
I lashed out to son too. Dragged him to school, had to ‘force’ him to make his homework, was sitting on top of him so to speak, made him cry (a 17 yr old at that time) and cried together!
Paid everything, school, cloths, driving lessons, etc. His mom? Not a cent!
He succeeded for his exams and for his next one.
(O, mother -exw- twice didn’t show up at his graduation! How hard can you let your kid fall, hurt so deeply… well she could).
Sadly, since a 2 yr. now, moms words were so filled with powerful magic that he started to lye, started to ‘forget’ our q-time, had ‘other’ obligations with family…
So pulled out of the gutter, supported him where I could, etc. and ‘mom’ is more lovable…
As moms promise to me once was:
“I shall destroy everything that is precious to you, also the relationship with the kids!”…
Please be careful, please talk and talk and please read about all.
Literature shows, among dr. Craig Childress and David Mallen MD, that PAS is common where a parent shows at least treats of Borderline or Narcissism.
https://drcraigchildressblog.com/2015/03/06/understanding-the-childs-experience/