My partner and I are getting ready to go to court for custody of his 5 year old son. There was no agreement made in mediation due to the mother doing everything in her power to keep their son away from his father and myself, mainly because she is still upset that the relationship didn’t work and he has another child with me. I created a facebook page and used my sister in laws name and picture (with her permission) and started talking to the mother of his son to find out exactly why she refuses to let him be in his life. I talked to her for a little over a year and found out exactly what type of woman she is. She disclosed all types of information and I was also able to print several pics of her partying while her son was her friends care. My question is will the 420 pages of facebook conversation proving that she is alienating him from his fathers affection and proving that she is an unfit mother hold up in court??

Admissibility of evidence is ultimately up to the judge, but you could certainly try to use this information.