If she is denying you court ordered visitation, then simply file a police report every time. Always carry a copy of your decree with you, and if she is more than 30 minutes late, file the report. Ask the police to escort you to her house to pick up the kid. If she refuses, the police can document that too. THey probably won't enforce the visitation, but they will document. Be very nice to the police, because they won't help you unless you really kiss their butt. Don't get mad with them, just ask them to file a report of some kind. You are only asking them to document the violation of the decree.
After you do this a few times, either the police will become more helpful, you will get your visitation, or you will have good evidence for your judge when you request a contempt citation. If you get the contempt citation, repeat that process until you have accumulated several contempt citations, and then request custody reversal based on repeated contempt.
Use your X's belligerence to your advanteage, and it will be a long process. If you check our TN links, there are some other groups near you who you may wish to contact. Good Luck.