If the stuff you have to sort isn't about kids, I'd be inclined to get a solicitor to deal with it all.
If it's things, see if you can get a police escort to go with you retrieve them. Otherwise, leave them. They aren't worth the hold he had over you.
If your name is on any bills he could run up, phone up and tell them you've moved out. They can write to him for renewal.
Always remember, he is going to do everything he can to suit his agenda. His agenda: 1. Con you into coming back. And 2: hurt, belittle and make you as insecure as possible.
2 is ALWAYS his agenda. So it completes with 1 because he just can't hide it sometimes. Hence the ease the nastiness shows through at the slightest challenge to his fisad.
You need to think as if you were him. With what he has, how will he look to hurt you? And how do you stop that? The best route is sometimes to stop caring about things: eg, items left behind. Just let them go, they aren't worth the joy he'd take in making it impossible for you to get them and, likely, damaging them.
It's hard because you've been trained to placate him to keep the peace. Now you need to learn to stop that. To withdraw from him and keep pulling until his nasty little tendrils break away from you one by one.
You cannot reason with a hungry bear. It doesn't want what you want. It wants to eat you. Do what you can to minimise contact.