What do I do if my son's father is going into court telling the judge what I said on my motion to modify are lies?

I filed a motion to modify my court order for the second time since my son's father has not had any over nights since July 2010. Current court order states 50/50 custody which is not the case anymore. I am unable to modify my child support since the court order still shows he has over nights. My son has had zero overnights since July 2010 when my son made the decision at 13 that he didn't want to spend anymore time with his father. May 2011 I sent in a motion to modify and got a hearing which father did not show. Tried just to modify child support and father did show, but said he was too heart broken to attend first hearing. He did not contact my son for 14 months after my son told him he didn't want to see him. Now he is telling my son that what I said in the motion are all lies.