You can’t legally change the locks and trying to would just escalate the situation. Ignore all that.
Small important things, you can do. Well done on already not cooking for him! With the washing, just leave his stuff behind in the basket, no need to say a word. If he makes any kind of dig say as calmly as you can “there wasn’t room for all of it” (if you want to be indirect) or “we’re separated, I’m not doing your washing”.
Spare room... not the end of the world if it’s a decent bed, I’d just pick my battles.
Go to a solicitor and serve him with divorce papers. Take control. You don’t have to have decided on asset split to do that. It also doesn’t mean that you’re leaving asset split up the courts - you still do it yourself, it only ends up in court if you don’t agree it, way down the line. It even has to be after mediation before a court will hear it.
Take the wind out of his sails by starting the divorce. Take legal advice on how you can proceed with regards to living arrangements. You can’t just make him move out.
The most important thing now is:
- do your sums
- make sure you get copies of all financial paperwork whilst you have access to it in the house
- see a solicitor
- practise letting his crap wash over you. If he’s on a night out? Good news you’re not looking at his pathetic face
If you have a chance for some weekends away (with or without kids) - visiting family or friends so it’s free - that may help. I lived with my XH for 4 months, albeit in a much calmer situation, and that space really helped.
Good luck!