What you described with your son coming around in the middle of the night and threatening to smash the house up is terrifying (sorry if I misunderstood that). You know your own son and what is likely to happen, but if you think you are in danger from him you do need to act on that, and put your safety first.
I am really sorry to think of you dealing with this on your own, its hard to refuse them cash when they are stood in front of you demanding it, but they have no control and will take everything, and when its all gone.
If you live in a city there are family groups that mutually support each other, or online if there isn’t one where you live. Famanon list them and I think that Adfam and Drugsfam do as well. It doesn’t solve it but it somehow gives you strength to draw on when you are being worn down by all of this.
Good luck