OP, this thread is resonating with me a lot. It has left me thinking for days... My exh was a very selfish man, but he was never violent or down right nasty, we divorced in good terms and continued to be friends for a number of years.
So we split and found new partners, and rubbed along ok until he met
his current partner... Jesus, I do really think she is far from abusive and controlling, she has substantial psychopathic traits, traits that I can see in this girl. It is the constant manipulation, outright lies and the way she has managed to make a normal person become a broken shell of himself who is capable to hurt the people he loved to protect a relationship that is not under threat.
Nobody he knew before he met her is longer in contact with him, we all took the step back and let them be to avoid upsetting her and to avoid ex going in Romeo-Juliet mode. But nothing was enough, I immediately got out of the scene, but she insisted we shouldn’t communicate about DS at all as this was “proof” I wanted to break their relationship, she also hated DS to a point she tried consistently to hurt him. We saw exH go first from a normal confident man to be a very aggressive man defending a relationship from a threat that didn’t exist to the point I had to seek protection from police. What was really strange was that I was no longer communicating with him at all but she was still pushing him to hurt me. DS told me that when he was with his dad, she was constantly shouting at him “but why is this happening? Until she made him cry, yet she wouldn’t stop until he said that whatever was happening, was happening because of me.
We have no contact with ex at all, but from time to time people I know bump with him. I do my best to avoid talking about him as I fear him so much these conversations upset me, but there is a pattern on what people say, he looks like a broken man, the confident person he was is no more and although we have not communicated with him for years on end he is still claiming bitterly that we all are trying to destroy his relationship.
The big difference in this case is that exH is much older than your son, and I’m pretty sure she will not try to kill him as he is the hen that lays the golden eggs, nothing could have been done to “protect” him from her. Your kid is 16, there are things that you can do and I can assure you whatever you do is going to damage the relationship you have with your kid, so forget about how your relationship is going to be impacted and focus on protecting your family from this psychopath.
She is not a lost girl that needs to find her way, counselling has no effect in these people, they are what they are, if anything she will use that counselling to build a case against you.
Your main focus should be not saving the relationship you have with your son, that will be gone whatever you do or stop doing, your focus should be to keep yourself, your son and the whole of the family safe by accepting all the police protection available and stop handing him to her in a plate, she will destroy him no matter how much you stay out of the way to keep her happy.