Change your numbers. Your fiance can just tell his children his new number, and you and your family members can do the same, just tell people you want to have your number your number. Your phone company may also have a function that blocks this particular caller/texter.
Your alternative is to seek a restraining order against her, which may only encourage this nutcase.
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My answer is based on the understanding that your fiance's ex is the mother of his children.
You and your fiance should change your phone numbers. You can give the new number to those that you want to have the number. Depending on the age of the children, he can give them his new number directly (instead of giving it to their mother). Of course, if the children are not of an age to bypass their mother with this information, then him changing his number will not help.
You and your fiance should also seek a restraining order. That she is entitled to the number as his co-parent does not mean that she's entitled to harassing him through the number. (Note: if you intend to attempt to obtain a restraining order, you should keep the messages and/or obtain a transcript of your text messages directly from your cell phone provider/carrier.)
You and your fiance may also press criminal charges, and/or file a civil complaint, against his ex for harassment or some other charge related to her behavior.
The above answer is a general explanation of legal rights and procedures. It does not constitute legal advice. Nor does it establish an attorney-client relationship between the individual posting the question and the attorney providing the answer.
Ms. Eyo has given you good legal advice. I want to add a few thoughts. First, I would STRONGLY recommend that your fiance consult with an attorney. Posting a question on a web service, like this, has only limited utility. Your post is troubling enough that I think your fiance would benefit from a sit-down consultation with an attorney, even though this will probably cost a couple of hundred dollars to do so.
Second, the wrong person is asking questions. You may be stuck in the middle because your fiance has children, but he is the one that should be seeking solutions. There is no reason for you to EVER have to talk to his crazy ex and there is NO reason for her to have YOUR phone number.
Third, which briings me to a non-legal point ... if your fiance won't take the necessary steps to stop both of you being harassed, if your fiance was so stupid as to make babies with a nutcase, why do you want to call him your "fiance"? Your friends and family are better positioned to advise you on the wisdom of this relationship, from your perspective, and I would, at the very least, ask them what they think you should do. If this harassment is troubling you as much as it seems to be, you have to decide if you really want to marry your fiance's "baggage" as it will only get worse after the weddinig. Just a friendly thought ... Good luck! Jim.
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