He almost lost his job -- sooooo because he was about to lose his family and his job, he went to rehab, sobored up and life was great. For about 6 months. He didn't go to address his problems or look at himself -- it was to save his a**.
That sure doesn't sound to me like someone who is "kind of halfway to trying to get better" he sounds like someone in deep denial about their disease. Many of us die of the disease of addiction. Only a fraction of us recover and don't relapse. Do you want your life to keep spinning out of control?
Recovery is possible only for those who really really want it, because it's hard. The first step involves a complete acceptance of the disease. He doesn't sound ready for that.
You don't have to go down with this ship. Save yourself and get some distance for you and your son. You can always go back to him if he gets sober for a year or so consistently. But why stay in this situation? I don't see it as benefiting you and your son in any way. You deserve better.
KJ