Not only can your S2 become like you and your S12, but he will. Unfortunately, he'll always have the negative impact of B in his life (which will remain a negative as long as she's running from her own issues), but remember how strong of a counter-balance you are and will continue to be.
Yes, he may have a more difficult time than S12 did b/c of their mothers, but the common denominator is still you, my friend. Don't discount that at all. To do so would to be doing yourself a grave disservice.
As for the need to get into a routine, I couldn't agree more. I'm in the same boat myself and am hoping to get something started as soon as things settle in w/the new school year (they're close, but had some unplanned things crop up last night and tonight is "back to school night/meet the teacher night" for D6, so my routine will need to wait another day.
Keep moving forward. You know the path and you travel it well, my brother.