First of all, it's very confusing when you refer to your STEP SON as your son. As in "Our son", "we allow visitation for MY son" etc. And, it's bad bad bad in court.
Secondly, going to the school to visit her son is NOT visitation. It's not going to be seen that way by the court, or anyone else. The school, barring a restraining order, CANNOT prevent mom from stopping by and having lunch unless they also prevent ALL OTHER PARENTS from doing so.
So yes, you were wrong and the school is wrong, and I suggest that your husband STOP NOW.
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