Do you have friends/family who could put up you and the children so that you can leave? If so, gather all the info you need, get out and start a claim for universal credit.
Would he leave if you told him it's over? If so, do it!
If not, things are trickier.
He earns good money. But he's mean with it, and hates me spending it. We had a relatively inexpensive UK holiday this year that I was told would have to come out of 'your money' (the benefits). If I lined up every can of beer, bottle of wine and packet of fags he's bought in the last year the price would be double that of our holiday.
This sounds like financial abuse to me. The DLA you get for your child is to meet the costs caused by their disability. The CA you get for looking after him is a token payment to reflect the fact you have sacrificed your earning potential to care for your disabled child. If your "D"H is controlling the family spending to the point that you are having to use disability-related benefits for a family holiday, while your DH earns enough to cover the cost of that holiday, that is very mean indeed.
You definitely need to see a solicitor and go armed with all bank statements etc.
I would be entitled to UC, I think,as I am a f/t carer to autistic DS. I get DLA for him and carers allowance for me. No child benefit because we are above threshold as a household atm.
That may depend on whether you can start living apart.
I think it unlikely that you would be entitled to UC while living under the same roof. You would have to establish that you and he were leading entirely separate lives to be eligible for benefits. Unless you can do this, you would be treated as a couple for benefit purposes and his earnings would almost certainly be such that your entitlement would be nil.
It is incredibly hard to prove "separate lives". You would have to demonstrate that you and he were eating, cooking, and shopping separately, that you don't spend time together in the evenings/at weekends, that friends/family do not regard you as a couple, that you do not share a room and so on. There's also a bit of a catch-22 in that they would regard you as a couple because he's supporting you and the children financially. (Sorry, should have said - I'm a benefits adviser.)
I think you need to speak to a solicitor first. I also think you should start an escape fund and squirrel some money away.
Once you know more about how/when you can start proceedings, you will be in a position to decide what to do next.
He sounds like an absolute shit and I'm not surprised you're depressed. 