I second the suggestion of Al-Anon. It's tough, but we really need to keep our helpful little noses out of our loved ones' recovery. It's possible to be supportive and encouraging without getting enmeshed in the minutae of their working their own program.
I don't know what's best for preparing young kids for a parent's (or the equivalent of a parent's) absence due to rehab. You might contact your b/f's rehab for suggestions--I'm sure this comes up a lot.