It's like I was reading my own story. My ex is the exact same way!! I'm so sorry that you're going through this, and I don't have a lot of advice because I'm still struggling with my ex 8 years later. Some people are just poison and unfortunately he has an advantage because the courts are so used to seeing dead-beat dads that they give a LOT of leeway to dads that "want to be involved" no matter how they're going about it. I think this is criminal. I can't stand it when my ex lies in court and the judges buy off on his BS, even to the point of refusing to see my evidence that PROVES he's lying. I truly don't get it.
I just wanted to let you know that you're not alone. If you can afford it, then you need to be holding him in contempt of court when he disobeys the court order. If you can, you should also be getting some counseling for yourself. A good counselor can probably give you tools to help you deal with him.
Most of all, just be there for your son and make sure that you're not saying negative things to him about his dad. When he gets older, he's going to know who the GOOD parent is, guaranteed. Your ex is playing with fire by behaving like this. One day his son is going to tell him to take his venom elsewhere because he's not interested in hearing any more of it.
Best of luck to you.
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Edit: I just thought of something else. Most courts have a family mediation service that is free or nearly free. You can call them and ask for their help. They will work to get the two of you to a compromise that is acceptable for everyone. You don't HAVE to do anything that they say, they are only there to be a neutral third party and work with both people to try to reach an agreement. They can, however, write up a mediation agreement that you can then have signed by a judge and it becomes a legal and binding court order. If mediation doesn't work out, then you can take it to court and make sure to tell the judge that you tried mediation. Just make sure that you keep a record of what goes on in mediation, even if it's just a journal that you're keeping, so you can remember it all when your day in court comes around.
Some of the things you could ask to have included in a new agreement is that neither of you can encourage or force the child to call a third party by "mom" or "dad" and that neither party can speak about the other party in the child's hearing etc...
Anyways, hope that helped.