Dear B
I know this will be costing you energy.  You may be surprised at your reaction when he goes – you could feel flat – i think it is the nervous energy being released to make way for good vibes – which will come.   Be prepared for some bad behaviour between now and departure time but keep doing all you have been doing – you will have a nine weeks peace and in that time you will recover.
He will be terrified – CGs do not like the unknown – actually I suppose we don’t either!   I am glad he is still saying he wants to go and really pleased that your family and the giggling baby are behind him.   Let him know you are aware that he is doing this for all of you and that you will be alright although you will miss him
One thing I think it would be good to talk about before he goes, is the amount of communication there will be between you if they allow phones and mobiles. My CG was not allowed a mobile and we had no contact for 6 months.   It gave him and me the freedom to really work on ourselves.   I used to phone once a week just to make sure he was still there. I know that mobiles and phones are allowed in some rehabs. It would be a good idea, I think, if you talk about how much contact you want before he goes.   In my opinion the less the better – it stops the questioning and allows you both to get on with what is important for both of you – a gamble-free life.   Recovery is selfish – has to be.   I’m not sure how you broach this subject but I think it is easier before he goes because discussions on phones when you can’t see each other are more difficult.
I am only going to do the Serenity prayer at the end of Tuesday’s group, at the moment but knowing you were there we did it last night too – specially for you. 
I am glad things seem to be moving forward