I'm sorry to hear of your dilemma.
Unless you and your husband are in the middle of a divorce, your husband can not prevent you from taking a vacation with your children to visit Romania. Only the court
can prevent that. If he fears that you plan to leave the country with the children and not return, he can ask a court to order that you not leave the country with the children. Other than that---you are free to go, so long as the children have their Passports. Because they are also Romanian citizens, you might consider getting them Romanian Passports as well, for future use.
It is not kidnapping to take the children on a vacation. Now, if you intend to never come back---that is a different story and that would be illegal for you to do at this point in time.
I wish you and your family the best this holiday season.
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