The prenup is not voided by such actions.....merely that the definitions of "Separate Property" and "Marital Property" will define certain assets that used to be separate as now being marital. If you want to fix the problem then amend the prenup (now a post-nup) and rejigger the assets/accounts to get them back into place where each party wants them to be so as to prospectively have it all in proper order again--assuming both parties are willing to do this.
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