OP, if you are real and if you are reading...
My family were also 'professional' types (teacher, accountant) and though the abuse I suffered at the hands of my mother ('only' emotional abuse, and not anything like the horrific scene you describe) wasn't as bad as the abuse your children are suffering, the similarity is that my father would sit back, as you are doing, and do nothing. Nothing to reduce my mum's rages, nothing to stop her saying violent, hurtful things, nothing to stop her crossing the line for the sort of thing you should ever say to children. N.O.T.H.I.N.G.
He was a grown man and he could - SHOULD - have made her get help, or at the very least tell her, just once, to STOP.
fwiw I had two nervous breakdowns in my early 20s, and a lifelong eating disorder, all because of my sky-high levels of anxiety. I never felt safe in my own home, not because of physical violence but because of the uncertainty of angering an abusive, boundary-less adult.
I still suffer pretty chronic anxiety to this day.
Years and years and thousands of ££ worth of therapy have helped, but not solved the problem.
I was only lucky that I found an amazing DH who helped me out of it all as otherwise I think I would just have fallen into a pattern of bad relationships as I didn't really know what affection/safe feelings are.
I was bullied at school too - I think kids pick up on another child's unhappiness and insceurity and it can make them a target.
I wouldn't wish it on anyone and in all honesty I don't think what happened to me was anything like what happened to your son.
Just letting you know that no matter what you tell yourself - and I have never been in your precise position so I can't possibly presume to comment on what is going through your mind to tolerate this - your children are suffering.
If you're real, I hope you're trying to find a way to get out.
If you're not real, well then I despair of the world a little more than I already do.
Some v v good advice on here and I hope you can understand why some people are very upset, this is triggering for a lot of people - if real. I'm definitely one of them and can't stop checking the thread to see if you've come back.