deadbeat dad

sorry but need to rant: so I have 2 daughters with my ex. a few months my 12 year old started displaying defiant behaviour, poor grades so I mentioned to dad she get counselling because this separation is hard on her. disagreed with me. around Christmas he didn't pay support so I obtained a lawyer. Because he has a history of not paying for long periods of time. through correspondence with lawyer he agrees that she needs counselling (covered through his group benefits at work) one minute but will not contact benefits for me to obtain the service and disagrees the next saying it is solely my financial responsibility to get her counselling. she is very defiant, refuses to do chores, does whatever she wants, refuses to pick her sister up from school. this turns into nightly screaming matches in my house with her step dad, me and her. And now I feel I need some sort of support with her behaviour. when she does something wrong at my house dad says don't do it again and then rewards her with things like promises of baseball games. fast forward to last week he told me he's changing jobs (quit to work part time) can't pay support when he should and he will determine the new amount based on his income. I'm at wits end and now he wants to fight to have her because he won't have to pay support. help! similar situation advice. does karma eventually bite dad in the ass or does this go on forever?