Hi Miller, Congratulations on 6 months !
It sounds to me like you both have put in a lot of work. It also sounds like your still working on it. He is active in outpatient groups support, and NA support groups. That is still a lot !
I do know what you mean about that feeling asking is it really over now, has change happened. Lots of people make the choice and stop. Your husband has been doing all that is recommended. Proper professional treatment, changing his life to make drug use incompatible, and now using a support system.
National Institute of Drug Abuse says that IF people get proper treatment then 40-60% NEVER relapse. Yes, that means 40 – 60% will at some point, but that is just part of the chronic condition of addiction. Its not failure just a sign more treatment is needed, or a renewed commitment.
Enjoy this time. Hopefully it will just continue to get better as you go. Keep building a healthy life for yourself, and as a couple.