Can you try and get a third party to read his emails to you to convey the facts only without his choice of negative words. His words (which are toxic) via email and his words via solicitor are what’s getting you down. They are poison so any contact is like ingesting poison that’s why you feel awful. I was told to try and choke down the communication to a mere trickle (due to us having kids together).
If he knows his words/intentions are not getting to you, hopefully he will try secure another victim but if he senses his contact is getting you down and affecting you and getting himself into your head, he will continue. They want attention. They want all attention to be focussed on them. If you only get the information he sends your way conveyed in someone else’s words then it will cause you less angst.
Apparently though they can always attempt contact (hoover) even after decades. they will always chance it to get some fuel (reaction) from us. But we can take control and resist their attempts at hovering us back into their world.