He is abusive OP. You should never be scared of a partner. You should be able to tell them NO without fear of consequences.
Don't let him blackmail you. All it takes for a relationship to end is for one person to want to end it. You don't need his permission or agreement to end the relationship. You don't have to pay him to leave. You just divorce him. You can both live in the house until divorce is finalised and house is sold.
Stop doing anything for him once you've informed him of the divorce, which should be AFTER you've spoken to a solicitor and Women's Aid about when is the best point in time to tell him. Once he knows, stop doing any laundry for him or buying/cooking any food for him, don't give/lend him any money or pay towards his debts, don't have sex with him or share a bedroom/bed. Don't let him drive your car, don't give him lifts and don't pay for petrol/MOT/ insurance/repairs for his car. on't tell him your personal business like who you're meeting or where you're going when you go out. Once he knows about the divorce he isn't part of your life any more even if you're living in the same house. You don't even have to talk to him if you don't want to, especially if he's being rude, unfair, insulting, disrespectful or abusive.
He is financially abusive, controlling, emotionally abusive. Speak to Woman's Aid about joining a confidence building course, they run them. Ask them for help making a plan to leave. You're in a good situation in that you can afford to live alone and don't need help from anyone to house you.
Speak to your mortgage provider about taking a payment holiday and tell the estate agent you need a fast sale. Try not to move out until house is sold because otherwise husband will stall the sale endlessly, he'll have no incentive to move out if he's living there alone and not paying for the mortgage.
Be realistic about your finances, if you have to live in a rented 2 bedroom house/flat for now and your child go to state school, then so be it. The main priority is exiting the relationship, not finding the perfect new home. Wanting to maintain your current lifestyle isn't a reason to stay in an abusive marriage. It won't even be possible, he's not going to contribute financially anyway, he'll just get more and more in debt.
After you've told him you're divorcing him, contact your old friends, tell them you're leaving an abusive marriage. See if they want to be back in touch with you even just to meet for coffee now and then.