Honestly, I've seen a lot of people go through the whole Rehab, NA thing.... it doesn't' usually work. What seems to work is flat out telling them Quit. Now. Or we are done.
Period. the end. No B/S. Find a doctor to help him safely detox (or send him to a detox center) and then tell him this is the end. Get your family to help you if they can. Holding their hand, and being sympathetic and "caring" will only let them know that if they screw up you'll do this with them all over again. The whole "one day at a time" system in AA / NA gives them the hope that maybe, maybe tomorrow they COULD do coke again...if they wanted to.... they just have to choose not to. It gives you permission to "relapse" by saying "you are diseased, and you can NEVER give up this substance without doing these steps, confessing to this, accepting this God etc etc" (IE..if you mess up, you have a disease to blame.)
You also need to protect yourself and kids. Ban ALL illegal substances from the house (if God forbid someone finds it, Family Serivces will take the kids and sort out who's it was later. And I PROMISE you, he's not going to smile and admit to child endangerment to get you off. I'm not not exaggerating or kidding. I watched DYFS take my friends kids this way. She was clean.) If you don't think he can do this - throw him out til he can. (I mean like THROW him out. Pack a bag for him and change the locks. If he's lied to you this long, he's not above doing it again.)
I'm not trying to be harsh, but this man does not have YOUR best interests at heart. Cocaine doesn't stay in your system very long - he should be able to detox fairly quickly (and once it's out of your system, the wanting it is ALL in your head

)
Good luck - I hope you can work this out.