Step parent problem

I’m desperate to seek guidance. I already tried to get full custody once, but it didn’t pan out due to child’s dad not having incidents on his discipline record at work and I couldn’t afford to keep pursuing since we’d have to start digging into his department integrity. Child’s dad is now married to a girl who is harassing myself (child’s mom) and my babysitter. We’ve got a police incident report for it. I live in a different state just to stay away from them physically but the wife keeps harassing me and posts about me to her Facebook and gets family involved. To the point, she doesn’t want to see my child (her husbands kid) nor wants my sitter to keep him because she doesn’t like me. How can I protect my child from Tennessee if he visits dad in Texas with stepmom around? We all know abuse to children is usually caused by step parents. His dad is a cop and refuses to tel his wife we’ve got a police report and I’m pursuing a custody amendment