ready to rip my hair out!

I posted a message yesterday but no one replied to me so here's more info. My ex husbands new wife is a manipulative control freak. She starts trouble at every opportunity. The last thing she did was tell me that I couldn't go to an eye appointment for my son(and even told me the wrong date.) She and my ex make my son call her mom, and when they got the list of supplies he needs for school. she went and bought everything on the list. They enrolled him in the school where they live without consulting me, and failed to put me down as his mother. Can I legally put a stop to this? There is definately a pattern to this. Will a judge even want to hear this? I live in Upstate New York. I am single living with my parents in a small town and they live in a small city. I have a 15 month old but am not with the dad anymore. She has two kids from a previouse marriage. My son loves them. My ex and I have joint physical custody. My son is with me for 3 days then with dad for 3 days and so on. Any advice on how to handle this because I am ready to rip my hair out. Thanks.