Hi Purple—
Remember that there’s a big difference between:
— the c**p he threatens you with when he’s trying to control you with fear and manipulate you, the things he accuses you of doing, all the idiocies that come out of his mouth, none of which need responses (you do not need to justify or excuse or explain yourself—it’s only an invitation for more abuse).
— the things he or his lawyer do legally—in court, in paper form, and so on, which need PROOF or at least some kind of legal justification, at which point you will have an opportunity and a couple of weeks to respond.
Just from hanging around divorce court (NOT a great place to be) has taught me that shenanigans from any side are recognized as shenanigans by everyone there because they see this kind of behavior every day they come to work, several times a day. (After my wife started telling everyone in the court what they should be doing, even the court officer got involved and told her to sit down and shut up).

two suggestions: make sure your paperwork and any proof is out of the house in a safe place he can’t take it from—a trusted friend, your Mum.
I read one book about splitting from an abuser (I’m sure there are many more): “Power: Surviving and Thriving After Narcissistic Abuse” by S. Arabi. And keep reading the articles and posts at Psych Central—information and understanding will help you.