Oh op, how awful :(
I read your first post and was going to say 'oh but she wouldn't have known all the dacts', and also 'heart in right place'
but then I read the rest.
You need to see the ht first thing tomorrow.
Emphasise that h is manipulative and gets people to help him to very very harmful things. Perhaps remind her that abusive men do not seem abusive to anyone at first, and that is why women fall in love with them in the first place! And that the teacher has let herself get sucked in - and that is
A. Unprofessional
B. Terrifying for you - massive breach of trust
C. Actively harms your sons well being
D. Has embarassed him in front of his peers, by making private business public
And what on the surface is a slightly over reaching thing to do, in these circumstances just has to stop.
Ask the ht to investigate what else was shared and how much this teacher has now become 'on h's side', as this is really dangerous. Tbh this doesn't sound like a teacher who would have the right reaction to another attempt to take your son. Maybe she would be great - but her actions plus his abusive manipulative behaviour means that this has to be called into question. You need reassurance on this ASAP.
Of course I don't think you should panic or go in all guns blazing... As that could fuel any nasty little thoughts of h = misunderstood by evil over reacting partner. Take the opportunity to emphasise how reasonable and great you are. I know it's rubbish to even have to think like this, but this man sounds like scum, and you need to protect yourself on all fronts.
Poor you. Many hugs and tea and many many 'you're great and you've got it in you to survive and live well with your ds'