You don't owe the bastard a timely response. Maybe give him his signature so he'll leave you alone if you're feeling magnanimous. He lives in another state so it's unlikely he'll show up on your doorstep.

It sucks when they unexpectedly show back up in our lives, doesn't it? I know it was destabilizing for me when it happened 2 months ago and I didn't even get actual communication only notified that he was trying to communicate. I imagine getting actual communication is even worse. You can do this though. Maybe reach out to Info for some support if you feel that would help?