I am assuming from your question that you and your spouse are now living separately. I am not aware of any law in New Jersey or any other state which expressly forbids a boyfriend or girlfriend from staying overnight when children are present. However, the courts have looked askance at such practices and have used it, in some instances, as a basis to grant child custody to the other spouse, especially when the children are upset about the presence of the boyfriend or girlfriend.
I suggest that you call me at 212-370-1660 to arrange for a meeting or call your local bar association to locate and experienced lawyer-mediator who is specially trained in divorce mediation.
Leonard M. Weiner, Esq.-Divorce Solutions