London, get copies of payslips, p60, pensions, savings, shares, mortgage statement, bank statement especially evidence you put half into joint account and see a solicitor.
Him saying he will leave is his way of saying shut the fuck up, do what I say.
This man is hideous. His contempt for your other children is disgusting. They are his child's siblings. Please please please speak to your health visitor you need the abuse on record to help you get legal aid if needed. He wants you to have no savings and a crap job so he is more in control.
Pre nup - see a good solicitor.
You are going to have a fight on your hands with this man. His threat to leave will be retracted when you say okay then. He will say 'it's my house you leave'. He will rant, rage, threaten, belittle. Blame you for splitting up the family. Read 'why does he do that'. Keep posting here, the lovely mners will help you see the wood for the trees!
Please get real life support and get out.