I am so sorry that you are going through this. Its hard I know I have been there myself with the PILLS.
My RABF had a back injury and became addicted to his pain pills. Its a nasty rollercoaster ride that at times can be terrifying.
I would strongly encourage you to pick yourself up a set of books called Getting Them Sober. They helped me tremendously.
Its time to take the focus off of him and put it back on you and your kids. I know that is easier said then done but you have to otherwise you will find yourself just as sick as your husband.
The first thing I would do is get a seperate account for you so that you dont have to worry about him taking money out for his pills. I dont know your situation but that would be the best thing to start with.
Then like lies said I would read around here and find out as much information as you can about how this isnt your fault. That is typical for an addict to blame everyone else around them it takes the focus off of them and what they are doing.
Then I would start off with small boundaries that you feel comfortable enough with in setting. For example I would NOT engage in ANY conversation that has to do with drugs with your husband. It solves NOTHING. It only makes things more difficult. Once you feel comfortable with that boundary set another one and so on and so on. This will help you establish some confidence little by little in taking charge of YOUR life.
And lastly remember that this ISNT your fault, you didnt cause this, you CANT cure it, and you sure as heck cant CONTROL it. Your husband is an addict he is gonna do what he is gonna do. Read the sticky about what addicts do.
Keep reading and posting. Welcome by the way.