Your current wife will need to file a relative petition on your behalf and, if the petition is approved, go through consular processing. As for your ex-fiancee's K-1 petition, you can notify USCIS or abandon it by doing nothing else.
It is necessary to consider many other details that are not mentioned in your question in order to assess immigration eligibility, options and strategies for a foreign national who is married to a U.S. citizen, and who was the beneficiary of a K-1 non immigrant visa application filed by a different U.S. citizen fiance. It would be wise for you and your wife to consult with an immigration attorney who, after learning all of the relevant details, will be able to answer your question and then should be able to offer legal representation for the application process which often is significantly more complex than it first may appear.
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