The short answer is that you have not given enough facts to know. Absent abuse or certain other situations leaving and unilaterally changing schools and possibly concealing the child without a court order could cause serious problems for you. You really need to consult a family law practitioner in your immediate area. Family law is one area where I have seen a broad range of variation across the state in what judges will or will not accept as acceptable behavior by the person leaving the marriage at the start of the case, and local knowledge is therefore critical.
The foregoing is intended as legal information concerning the question asked, but is not intended as legal advice upon which the requesting party may rely in guiding their actions. Rather, the requesting party should consult an attorney for a personal consultation and advice for a full consideration of their situation and rendition of legal advice. Additionally, by providing this general information I am not accepting any representation of the requesting party and I am specifically declining to form an attorney-client relationship with the requesting party unless agreed to later after further consultation and agreement.
Areas of practice listed are are areas of concentration in my practice. I am not board certified in any of the listed areas, and by listing them and describing my practice I am merely describing my experience and the nature of my practice.