Sorry OP, I do hate telling you this, but this isn't going to work. You're no longer treating your husband like a husband, you're treating him like a teenager who the cops found with drugs and brought home. The thing about addiction is you're not going to quit until you're ready to quit, and the way it is your husband doesn't seem ready. You say all other aspects of your relationship are great, other then the crack binges; are they really? How does he really feel about how you're treating him? I can assume probably not the best, even though he agrees to it, it may be out of fear of loosing you.
Crack, and all cocaine for that matter, is extremely mentally addicting. It's what you want to turn to when things upset you, leave you feeling low,when anything goes the slightest bit wrong, and this could be how he's feeling. I don't want you thinking that you're pushing him towards drug use by this type of treatment, because that's not necessarily what I'm saying either but some things to think about.
Now-- To answer your what to do question. I think the first thing you need to do is have a long talk with your husband, as an adult, and figure out if he's really ready to quit. If he isn't, it won't work. He could go to rehab for a year, two years, five years, and within a few days, weeks or months of getting out he'll be using again.
Next, you need to start finding things for him to do, maybe together even if you're not ready to trust him yet that make him feel fulfilled. On a chemical level happiness and fulfillment are the same thing, and both cause the same release of brain chemicals ; a cocktail of serotonin, dopamine and other 'feel good' neuros, which the brain reads as a 'reward'. The action of this 'reward' giving your brain all the things that make you feel good teaches your brain to seek this out.This is very similar to what happens in your husbands brain when he smokes crack, as cocaine acts as serotonin–norepinephrine–dopamine reuptake inhibitor, and effects the mesolimbic pathway (a dopamine pathway which effects feelings of reward and desire). So, in simple terms, addiction is a form of learning gone wrong, due to lack of natural chemicals being released as much as they should be from lack of fulfillment, and the way to beat it is to teach the brain other ways to get the same kind of chemical releases without the middle man, in this case crack. (Which is, admittedly, easier said then done.)
Lastly, OP, you have to give your husband his freedom back. As a drug addict working through the long hard road of recovery, I know that having people who SUPPORT you is amazingly important, there is nothing more so important during it. Having people trying to force your recovery, or control it, is not. I suggest maybe a program like narcotics anonymous for him, and al-anon families for you might give you two some chance to get some support, and also some space. I know that it'll be hard for you, and I defiantly agree boundaries need to be set, especially in relation to family finances, but what you're doing will only make you resent each other in the end.
I'm sorry this is so long, it's my first post, I have to learn how to cut this down, but I hope it helps. Best of luck.