You’re doing all the right things-documenting, not engaging in her demands or rude comments, putting the child first, etc. Once you feel confident you have enough documentation for a solid case, hire a lawyer and proceed. Understand that laws vary from state to state but even with 50/50 you may be required to pay her some child support of her income is less than yours. Take photos of your home-your child’s room, common spaces, etc. Show text proof of you trying to communicate and solve issues like the school choice. It’s not impossible but it will take time and money. Good luck!