Ugh, what a charmer!
He may be ‘on a break’ but real life goes on!
Get yourself online to Turn2Us or another benefit calculator & check out what you might claim if you split - even though you may still live in the same place - to make sure that you can get by without his contributions. You could do that now or tomorrow.
While you are online, the Law Society has a searchable list of solicitors, look for a family law specialist in your area. Email a brief explanation & request for an appointment that works with your current hours for basic advice about your rights - get this sent so that it is there for Monday morning. Gather all documents & certificates etc relating to marriage, incomes/debts, house, mortgage, pensions, investments etc, make copies & keep originals & copies safe away from home or somewhere lockable. If he is a bit chaotic with money, I assume that he will also have some personal disorganisation (?), so make sure that you have all the documentation mentioned that you will need safely stashed.
Although you work nights, this is to your advantage right now as you are free during part of the working day to make progress. By this time next week, you may have a far far better handle on your situation by being better informed with better control of your life.
Who knows what he is up to or who he is with, what matters is what you do for yourself.
As others have mentioned, do nothing more for him: no cooking, no shopping, no shared meals, no washing, no more financial support. Nada. This is important as you need to prove that you are no longer living as a couple should you claim a benefit. It is possible to claim as a single person & still living under the same roof which is in both your names. The Govt website about Universal Credit gives a definition.
The solicitor will give you practical advice about how legally separated couples cohabit e.g. reasonable requests about returning home so that the front door can be secured etc.
Hang in there, this has been a nasty shock.
Get good legal advice, protect yourself & your family by being well informed.
You will come through this crisis.
Oh, good advice from previous MNetters, don’t blub or blather at the solicitors, the meter is running 😉.