Serenity- are there any temporary support orders in place at the moment? He wouldn't have much of a choice about supporting his kids, temporarily or permanently, if it's court-ordered.
And I understand that moment of entertaining the thought of walking away without him paying a dime, I had the same thought myself recently. Stay strong, and keep fighting! I know it's tiring, but I'm sure this new strong, confident Serenity throws him off his game plan.
Keep taking care of yourself and little man- Hugs, Bunny