Well this is really quite something. I had a business partner who was about 50% as bad but reading this brought all that flooding back. You must be utterly broken. The healing only begins when you are believed and there's no contact, but he's relentless. Apologies if this had been said but your ex is a pure psychopath and this is going to be very difficult to beat - but can be done.
However coercive control is a tough one because you no longer live with him. You have verbal abuse and malicious court cases - difficult to prove and not quite crimes and him making life difficult for others and corrupting your son - difficult to prove and not quite crimes. He's good at the 'difficult to prove not quite crimes' and his 50/50 custody gives him the money to make life very unpleasant.
So this is definitely going to take a superior strategy - starting with no contact except via a third party. I would suggest his gf if she's long term.
Brainwashed though she is if you are reasonable and pleasant, keep it short and relevant there's little she can do and she's not him. Apologies as I haven't read the thread (I had to stop it's pretty upsetting and I'm just so sad and angry for you) 
so I hope I'm not saying anything irrelevant. The important thing is no direct contact at all. He does not have your number - though I have money on it he will create an 'emergency' to make you pay for not being available,
But I think the worst thing is the constant trail of people who believe him and give in. By now you're almost certainly presenting as un believable - it's what happens - and so you need to keep all the proof. In the end I didn't win though because I had that proof (though I did get a couple of allies who at least believed me).
You need someone ON YOUR SIDE who can tell you what his crimes ARE. And they do exist. All that stuff he's said about the baby etc. And then to explain what you say and how you say it and to whom - I've found they don't want emotion but when there is a rule broken.. bam. That kind of ruthlessness and rule following can be found in social services or some of the non mainstream DV help, so arm yourself with a list of events (timeline) bullet pointed with examples and start talking to people about finding someone that can help you for free. Don't talk about him. Talk about what he's done and what happened (learned the hard way). People SLWAYS want to see things for themselves 🙄 and so they need to be in between you and him so they get the brunt of it (my ex biz partner had people he didn't bother charming. Once my allies were in that camp it was game over for him. The mask dropped). Never underestimate his arrogance, which is a major weakness.
He's got away with a lot - no division of family assets for example. He's got 50/50 custody and continues to make life unbearable. So he's clearly articulate and coming across as competent. You need to do the same - hard when you're heavily pregnant and ground down.
I know a woman with an ex like yours. I remember her telling me her story and she won by getting her very own psychopath on side who took her ex apart just for his own entertainment. There's no way she could have done it - but she was smart. She found the right person, got them on side, and they just went for it. She got money, ex out of the way, and peace/happiness. The psychopath knew how he thought and where his weaknesses were. She was a lamb to the slaughter on her own.
We are all in lockdown so maybe trawl here and online and even make some calls. Pitch it as 'this man had managed to defeat everyone' and see who rises to the challenge. You need someone on your side who has what you don't - strength, balls (sorry, that's not an insult - but I don't see you telling him to fuck off and sending him harassing texts) and a willingness to do anything to win while you stand back and give them ammo in the form of proof. And who wants to win and fuck this guy over.
Use this time to find that person (or people). Not the police btw. Or probably anyone in the public services. They are too rule bound and not creative enough. Not someone you have to pay up front. but at the very least you are entitled to half the house, and don't let anyone tell you otherwise though I'm sure he 'proved' he had 'nothing'. But omfg courts hate that stuff - so if you go anywhere near a hearing inserting a line about the assets vanishing will get attention.
The good thing about psychopaths is they are predictable. They all do the same shit whether they are nasty, businessman exes, or serial killers. There ARE people that see through that you know. I thought after 11 years with the business partner there weren't - but there are. Big hugs, get another phone for friends and family and turn his one off forever, and write that timeline out. Then find those people who are in it because they fucking hate pricks like him and who will do it just because.
I got mine out of my life and you can get yours out - but only if you radically change tack. Good luck and big hugs x