I'm so sorry you have to go through this. It sounds like you are doing all the the right things and don't need any actual advice, just support.
Why does your ex think he can do that stuff? Very often, it's because they've got some sort of cluster b personality disorder. I haven't read this yet, but a friend recommended it to me just the other day, and from their description it sounds really good, it's called "Fuel: What makes the narcissist function?"
https://www.amazon.com/Fuel-What-Makes-Narcissist-Function-ebook/dp/B018W7XYZA
It's written by a self confessed narcissist. He's actually written a stack of books on narcissism. This one is only about 100 pages long, so a quick read. You might find you can relate a lot of it to your ex's behaviour.
I really hope you're able to get the support from the authorities that you deserve and can put this awful person behind you once and for all.
It is SO intense to have that realization. I remember when it finally hit me. It was like a new world opening, and I was flooded with SO MANY intense emotions.
Please be really kind and gentle with yourself during this intense time.
I’ll share a book that really helped me at that time.
WARNING- this book is written by a narcissist about his own thought processes. It is seriously disturbing to see how he sabotages and harms those around him on purpose. But I found that reading it brought me a better understanding of what it’s really like in my Moms sick head. It was like I HAD to read it, I had such a thirst to understand now that I was no longer blind to the truth.
fuel, by h g Tudor https://www.amazon.com/Fuel-What-Makes-Narcissist-Function-ebook/dp/B018W7XYZA