We have been separated for 12 years and I don't know where he is. He appeared in a local bar about 1 year ago where a friend of mine works and told her not to tell me. Do I need his signature after all these years. We have nothing together anymore

It will just take longer and cost more if you can't find him to sign.

There will have to be a search for him to serve him, If you can't find him costly newspaper publication and larger attorney fees.