Please know Moggie that this damage is all the responsibility of your FW H.
What you are and have been doing is trying to protect from his damages. In separating you are absolutely giving you both protection and space with peace and calm.
Try to write and record, here if you want, anything that you can to make his behaviour clear for you. This will be everything you need when /if it comes to any push on his part to take you to court for contact.
I am so sorry to hear that you have had to endure EA, but you are in fact facing up to all this and acting in order to protect your beautiful DS. He does need protecting, and staying put will not do that every day you stay he is subjected to more abuse. You are brave to have survived all this and will both benefit hugely from being out of it.
Your FW H is losing control of you (by your leaving) and that is the worst prospect he could face, so he is likely to threaten you, and he knows that the biggest threat he has over you is your beautiful DS, so naturally he will use that to keep control of you.
Courts are interested in children seeing both parents safely, and the schedule of contact that you are talking about is absolutely reasonable and fairly standard. With the knowledge of his abuse that you have, providing your DS is safe from that during contact, a court will wonder why he is pursing you for contact if he already has reasonable contact?
Many are only interested in the DC purely as a tool to control their DM. Once they realise that everything is sufficiently distant and managed for them not to have any element of control over you, sadly many lose any real interest.
For now I think it makes sense to not engage with him about this atall, and just quietly make your plans and separate in whatever way you do that. Do it as quickly as you can and let others know that you can trust 110% to not speak of it and to store things of importance for you, like all your passports, bank cards, statements, bills. DS's medical book, etc
Keep your head down and both safe, as this is the time he is likely to use everything he can to exert more control over you.
Welcome to the thread, but sorry you need to be here, but you are already a long way along on your way to having a better life for you both.