In 2009, my (then) wife disappeared interstate with our two young sons. A Recovery Order was issued by the Federal Magistrates Court and the children were located by the AFP ( Australian Federal Police) 3 months later in South Australia, and returned to me. I won full custody twice, as she appealed the first decision. I live in Victoria. On the last few access visits both children made allegations against the Mother of both sexual and drug related issues and accusations of weapons in the house, plus the younger son (then aged 4) arrived home after one visit with severe bruising to his buttock and upper thigh. He alleged that the ex-wife's de facto partner had repeatedly assaulted him with a wooden spoon. My older son also provided me with photos of drug containers, crack pipes, samurai swords and daggers that he took on his last access visit. He is now 15 years old. Police in Victoria had no doubt that the allegations were true but the files were handed over to SAPOL and were investigated by the Police. No charges were laid on any occasion, which did not surprise me as my ex-wife has a sister who has a girlfriend working at that Police station. The only action that has been taken seriously by them has been an anonymous complaint made by myself to S.A. Crime stoppers regarding cultivation of Marijuana at the premises. Plants were found as well as numerous crack pipes and bongs and fines were issued. During one of the final phone calls to my sons, the ex told my older son that I was on the Sexual Offenders Register because I had sex with an under-age female. The allegations are totally untrue. In fact I have never spend any time in jail in my life. My son is now aware that they are false allegations as I have a Working With Children's card, a Security license and have had Police checks done for the last 4 years due to my involvement with school councils and parent clubs, plus he asked a DHS worker who advised him that I have never been on the Sexual Offenders Register. Fortunately my son had also gotten into the habit of taping phone conversations with his Mother due to her offering to supply him with drugs when he was only 13 years old, so I have her accusations on tape as well as physical threats from her de facto. The ex also made the same accusation on her (old) Facebook page in December 2009. I have a screenshot of her Facebook page showing this, as well as accusations of 10 years of mental and emotional abuse. During the first custody trial subpeona's were issued for medical and criminal records. However the Magistrate stated numerous times in her 'Reasons For Judgement' that the ex was an 'inconsistent witness' and paid no attention to a Family Report that recommended that the children live with the Mother due to many lies that the ex told the Family Report writer. These accusations have caused my son and I much distress since then, to the point where I have been diagnosed with having severe anxiety bordering on depression. The Mother has not had any contact with the children since then. This happened in early 2013. However she has, since then, destroyed my relationship with my other two sons from a previous marriage and is now close friends with them. She also has written letters to my sons schools they were attending at the time. The schools will not divulge the contents of the letters from her due to privacy laws, but their once friendly attitude towards me changed severely to the point where I was forced to change their schools. I have also lost numerous friends since her post on Facebook. I am wanting to know whether I am able to take defamation action against her regarding the accusations?