While it is possible that there is some specific law or doctrine in your state that would prevent your ex-wife from receiving your life insurance benefits, that is very unlikely. You can name anyone to be a life insurance beneficiary, and until you change it to your current wife, chances are those benefits would go to your ex. Fortunately, it is pretty easy to change beneficiaries (usually with something called a Designation of Beneficiary" form).
In any event, I would certainly go ahead and change it.
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