Family court, I have proof my ex lied under oath?

I have sole custody of my duaghter, my ex (her mother) has rights to visitation and that is all. We got out of family court in November for a modification of visitation, during the time we were in court, my daughter told me that she had seen her mother boyfriend naked. I was pissed to say the least and reported this to the law guardian. My ex compleatly denied this fact and threw a huge fit that I was brainwashing our daughter and filling her head with things. Although the law guardian believed my daughter, the judge said he couldnt take the word of a 5 yr old against an adult, they had a child protective case opened and it shut with no findings. They basically told me that they found no danger and no reason for her mother to lie and wouldnt grant me supervised visitations like I had asked for becuase this is not the first problem with the boyfriend over stepping boundries. Previous to this a judge had ordered that my daughter not be allowed around the boyfriend becuase she was severly scared of him, we never found out what happened to make her this way as for weeks she had been fine with him. When her mother moved in with him, we modified it so she could go there but he couldnt be alone with her at all! Well obviously they dismissed the allegations and we settled on a new agreement. After we got out of court a few months went by and my ex and i have been very civil, she got preg by the new guy and stopped taking our daughter becuase the boyfriend had become mean and we agreed our daughter didnt need to be in that environment. Our daughter has alot of resentment toward her mother for the things she has been put through. Well last month I was talking to my ex on AIM and she was emotional. She fully admitted to me in full detail that she had lied in court and that our daughter had seen her boyfriend naked and that she was scared and lied so that people wouldnt turn it into something it wasnt. Supposedly it was an accident, he stepped out the bathroom naked to go to his room and our daughter was in the livingroom and saw him, yet this is only half the story according to my child. I am extremly angry and even more angry that it was dismissed even though i knew my child wouldnt lie about it. My daughter was put through hell called a liar by family and her mother and it truely hurt her. I dont know what to do now, she hasnt gone with her mother since early april and has only seen her twice since at our home for a couple hours. She doesnt not want to go back to her mothers at all!!! I dont know what to file or how to go about it again since the last time I was basically told too bad. I dont want my child going there anymore!! if her mother can lie about a supposed accident, what else will she lie about!!!