Jessers, I'm sorry you are struggling. I hope you will use this opportunity to recover from both your divorce and your relationship with an addict. You never know you may find some paralells in the relationships and if you take the time to learn and grow now, you may be able to end the cycle. There's another book out there called - The New Codependency - that a lot of people on here are reading. They say it's really good. Why not give it a shot and see if you can learn anything about yourself.
And Ninja, ask yourself, What's the best thing for my son? Do that and you will never ever ever regret your decision.