I have an order of child support that I pay. Is getting braces part of me covering his med insurance?

I made 44k in 2011. I am currently paying $188 a WEEK for my 14 yr old boy, who I have every other weekend. I am ordered to have med insurance for him. We were never married, and had him when we were 20. She (his mother) is remarried with a child of their own. He works, but she does not, and has not in the past 3 years, sucking up unemployment until it ran out. She still doesn''t work. I am married and have two children with my wife. My original judgement also slapped me with a 23,000 arrearage that accumulates 9% interest. I was paying $97 a week, but evidently that wasn''t good enough, so she went to child support enforcement and they slapped me with $188 a week. I am in construction and we have are slow seasons where I get laid off, My unemployment is $990 every 2 weeks, she gets $376 of that which is about 40%. Now she wants him to get braces and is giving me a bill for half. Are braces part of medical ins? She provides $0 to support him, can she do this? She is a dead beat, lazy, mom