Wow...I'm not sure I understand at what point he decided to join NA...recently?
Look on the bright side...if he really does plan on making a serious effort to stick with NA then perhaps his actions will change for the better, in the future. Any ammends he chooses to make, does not obligate you in any way.
The past is done, not much can be gained by continuing to look back. But that doesn't mean it isn't a lesson learned.
I have to admit that if either of my Ex's behaved in that way I would be as angry as you. As hard as it often is I've learned to try my hardest to let go of the anger...doing otherwise not only eats at me, but it fuels the fire...puts me at the same level as the one I'm angry with.
I'm not sure its the "healthy" kind of letting go of anger, because it often doesn't feel very forgiving, but its the closest I can get at this point.
Keep coming and venting (that helps me a lot)
Wishing you peace
((((Hugs)))
Cece