If your child is happy, doing well in school, has settled in and living her life, a judge isn't going to change the custody arrangement. There would be no reason to. There is no reason to worry about "slinging mud" in court. Don't even worry about what you know or may know about the other parent. Just focus on the kid. If their lawyer is saying they have no chance, then just relax and let this fizzle itself out.
Your ex and his wife can only upset you as much as you let them. So what if they do things you don't approve of, so what if she wants to stay home and not work, so what if they want to keep alive the idea your a bad person. Let it roll off you. It's only your problem if you let it be. Quit thinking in terms of how much better you see yourself than them and simply focus on your life and being a mom.
