adoption by step-parent

What is the name of your state?

Arizona. After our divorce my ex-wife moved to another state. I stayed out of the picture for two years. While we were out of touch, she had his last name changed without my permission. The last 8 months I have been working to pay back child support and trying to be involved and get back in the picture. Now my ex-wife is going to be remarried and wants the new guy to adopt my son. She says I don't have to give permission because I was out of the picture for two years even though I have been in the picture the last 8 months. Is there any way that she could do this without my permission and behind my back? Does she have to file for the adoption in Ohio or Arizona where the divorce was filed?

She is incorrect. If you stay in contact & pay support, she will have a hard time getting your parental rights terminated. She probably could have done it during the two year period you showed no interest, but not now.

You will be notified of any court proceedings.

She will file the petition to adopt in her current county.