This is so much bigger than hygiene issues. He has a lot of control over you. Www.freedomprogramme.co.uk
He won't change, he's made that clear, so if you're ready to find a way to move on then focus on dealing with your obstacles first. It's helpful that you already know change is difficult for you because you can begin preparing yourself to cope with it in advance but also do some planning to reduce the uncertainty.
So, look at your budget and what your finances will be like without him. Draw up a new budget as appropriate. Check if you'll be entitled to any welfare support you aren't now (eg try turn2us). Are there any changes you will need to make or any preparation you can do now? The Money Advice Service and moneysavingexpert may both be helpful.
If you kick him out, will you be able to continue living where you are now? Would you prefer the change of a fresh environment? Are you comfortable with everything you'd need to do to stay where you are now and get him to leave?
Do you need legal advice about any of this? Rights of Women may be helpful. Also Citizens Advice depending on nature. Otherwise, if you need to, book a consultation with a couple of solicitors (rather than just the first one you find) - some offer reduced rates for the initial consultation or will have an initial chat for free to point you in the right direction even if their fees will be too high for you to engage them... It depends on the firm, but worth exploring if you need to involve legal professionals.
Keep up the job search but also think creatively about childcare and explore whether any of the suggestions made on this thread could be viable, eg au pair. You do have the right to ask for flexible arrangements at work (which could include altering your hours) so find out the process and have conversations.
Don't assume something won't be possible until you've checked and talked to people. Sometimes employers respond much more positively than we'd expect, especially if they don't want to lose you.
You don't necessarily have to make the changes all at once unless you feel you need to for your own wellbeing (because of the clearly significant impact his behaviour is having on you) or because he's jacked in his job again and left you in a needlessly difficult position. Or for any other reason of your choosing!
You have some time here to plan and get everything sorted before you jettison him.
How much of a support network do you have around you for when you are adjusting to life without him? You've said you find change difficult, and even knowing it's the right decision the finality of the relationship ending might be difficult initially. Are there people in your life who can be there for you if it's rough for a few months at first?
It may be worth starting to tell trusted people in your life if you have any so they can offer you support if they wish to. They may have ideas, they may be able to do things you hadn't thought about, or they may just make you feel less alone with this. If you don't have people, there's here obviously but also Samaritans. You don't have to be suicidal to talk to them and they have an email service ([email protected]). You would be anonymous whether on the phone or by email (could set up an anonymous email address to use) so could talk about things you can't here or elsewhere. No risk of it ending up in a tabloid or someone identifying you.
I don't know enough to form a view on whether what he's doing is deliberate abuse (although some of it sets off alarm bells), but Freedom Programme teaches about healthy relationships (and even if this isn't abuse it's definitely not healthy the way he treats you) so might be worth seeing if you can attend one of the groups.
It's just information, not therapy, and there's no standing up to share your life story, but they're small groups of just women and really friendly and supportive. It's open to any woman whatever kind of relationship you are or are not in. The groups are free to attend and totally confidential - they don't even keep attendance records. (Www.freedomprogramme.co.uk)
It might be good for you to have that kind of confidence/backup in deciding in your own mind that you deserve better, you deserve a healthy relationship with someone who respects you, your DC deserve better, and from learning how you should be treated in relationships - as well as prepare you for the stunts he might pull to manipulate you when he realises you're serious this time about ending things.
You must have been young when you got together, and it sounds like there is an awful lot of deplorable behaviour on his part that has been normalised for you. FP could help you unravel that so you can have a brighter future that feels more hopeful.
Lastly, you're so young! Your future could be so amazing, but not with this man dragging you down and keeping you from flourishing. Ending a relationship that's been the basis of your entire adult life is scary but that fear is temporary and gets you to a much better place.
The sense of loss you might be feeling is of the dreams you had for your future with him, not the reality you're living or will ever have with him. Please don't stay just to avoid having to face your grief over those lost dreams. They've already gone.
Give yourself the opportunities to have a better life and better relationships with people who care for you, encourage you, and respect you. Focus on what you'll gain and why it will be worth it in the long run.