If you know you can quit smoking crack, why on earth would you make the decision to keep coming back to it every few weeks when you have seen what is taking from your life? That, my friend, is what we call powerlessness and insanity. You're doing the same thing over and over and expecting different results. Ask yourself, do you honestly, deep down believe that you have any control over using? Do you really think this is a matter of willpower? If so, then like you said... since you know you can quit, quit. But, going back in a few weeks is NOT quitting.... Actually, it might be easy to quit, but staying quit is where you begin to learn you are powerless... CRACK makes your choices.
My suggestion... get to NA... go to meeting no matter what, whether you're sick, high, sober, whatever. Just keep going no matter what. The sad, yet realitic alternative is death, jail or institutions. Ask yourself if you've had enough? Are you willing to lose everything else, maybe even possibly yourself? And what are you willing to do to stay clean?