You handled that whole thing PERFECTLY, its OK to stand up for the FAMILY, and you did it in a calm, yet firm tone, which garnered you some respect. If he wants to move out thats one thing, but the KIDS are not to come second, PERIOD. Gotta set those boundaries...
So, thats passed, now you move onto dealing with your S, and I know how tender thats going to be, but somehow, you'll find a way to hold things together...
Good luck, hang in there, this is just another bend in a long road...