What are my options if she wants to cancel her sponsorship?

I was approved for a green card based on i485 and because of an argument over my job, she told me to leave the house and that I can't see my daughter if I didn't follow her (orders). It was 1 month before I got approved for my green card. After getting approved, she filed for divorce and made info pass to the local immigration office. She gave them a letter with enclosed green card telling them on the letter that I left the house, that she don't know where I live and that the final decree divorce is in the process. I don't know what to do now. Here is the letter - January - This letter is to return the enclosed green card under the name of Mr. *********. The above named individual is no longer residing at this address. We stopped living as husband and wife as of ****, and I have no information of his whereabouts. Please be informed that a petition for divorce is already in process. Beforehand, I will greatly appreciate your assistance. Hoping in good faith, if by this means you can accept this notification letter as my request, to process the cancellation of my sponsorship Form 1-864 (Affidavit of Support) for the enclosed Permanent Resident Card.