I'm really confused. Everything about this is wrong but why won't he even spend money on his own children? He sounds like a complete and utter bastard. £110k net with no mortgage. And he's leaving you to pay for all family expenses out of an allowance that's so small you've had to sell your own valuables and go hungry to make ends meet. This is appallingly abusive. How is he not dying of shame inside?
He's even put you in the situation where your NI contributions have not been paid which has serious implications financially.
@Rocksandriches - it's clear from your answers that you've been somehow managing to hold this situation together for years and perhaps are only now realising how wrong this is. You've been in survival mode. You must be incredibly strong. But it's all wrong and no-one should be in survival mode in respect of their family life. You being an SAHM has been your job. It has allowed him all the freedoms he's got without having to pay for childcare costs. There is a huge financial value on that. But even if there wasn't, this is absolutely awful.
And I come back to this: why doesn't he want to spend money on his own children? Why would he keep them short in this way? Why would he provide so little financially that his wife, their mother, has to go without food?
In fact, it sounds as if he considers himself single. He's scarcely ever with you as it is and, of a salary of £110k p.a., he's allowed you £6.5k. I've just put that into our calculator - that's approximately 6% of his salary p.a. On his wife and children. On the people whom he should love more than anyone else in the world and want the absolute best for. What a bastard.
Ok, OP - one step at a time. Speaking to Women's Aid would be a very good place to start: www.womensaid.org.uk/domestic-abuse-directory/.
Also, you're married so you have rights here if you get divorced for financial support and in respect of the house. Do you have anyone you can reach out to in real life for support? Is there someone who could pay for you to consult a solicitor? Could your parents do this for you? It doesn't mean you have to divorce him (though I think you should because he adds nothing to your life) but it would be very good for you to speak to a solicitor so you become aware of what your rights are in this situation. You've lived with so little for so long because your H has bullied you into accepting that and perhaps because you weren't aware of your own rights in this situation. Knowledge is strength in this situation.