Sorry that you have to deal with addiction. It's not a pretty story, I can only hope that your husband embraces a strong recovery program and sticks to it. It is his problem, his choice.
With that said, I encourage you to start putting some money on the side, JIC money. Addiction can drain a bank account faster than you can fanthom. Put the money in an account in your name only.
I also feel that it is better for your hubby to totally suffer the consequences of his action. He can read to your son on the weekends, it is very important not to make excuses to do things for him.
Best of luck!