Oh, and one other thing. If he's going to keep dragging you into court anyway, I'd move to enforce the support order. Why not? If you're gonna be cooling your heels down at the courthouse you might as well ask for what you (and your KIDS) are entitled to.
Time to take off the gloves. Being nice hasn't gotten you anywhere. You don't have to be ugly about it, you can just file a polite motion to garnishee his wages.