You could only petition your ex-wife if you remarried. There is not a petition available based upon an former spousal relationship.
You could file the I-130/I-485 Packet (Petition for Alien Relative) and your wife could adjust status in the United States without returning to her home country if she initially entered the United States with a visa.. The entire process takes a little over a year and would require that she take a Biometrics exam and that you and your wife be interviewed by a USCIS officer who will determine if she married for the purpose of obtaining permanent resident status. If approved, she would be issued a conditional permanent residence card because she would have been married less than two years at the time that you filed the petition.
The I-130/1-485 packet is found at the USCIS website at uscis.gov. The marriage certificate is required to be included with the petition/green card.
After you are married, you and your wife should file the following forms with supporting documents:
I-485-green card application
I-765 -Work permit application
G-325A-biographic form for both of you
I-864-Affidavit of support
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