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I'm sorry to hear about your situation. I don't know if I answered your question before (if you asked it before).
I wish I could contact you with a phone call, but that's considered legal advice and counsel at that point, rather than answering a legal question, and as such is prohibited by the terms of service of this site. That option is there because there are many different categories on this site, but only one (legal) has such a restriction on forming an attorney-client relationship. But we can continue the question here.
There's no "legal standard" to sign under duress. That is, there's no magic language that will make it though you were signing under duress. Rather, under duress is a "question of fact" for the court to determine in light of the facts. Now you can certainly write out "under duress" (I would make it as clear as possible so that you could show it to the jury and not have to explain what "U.D." or "V.C." means). But even putting it as clear as "under duress" doesn't mean that the court has to determine that it really was under duress. It just means at the time that you signed it you wanted to express what you felt.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (3 or more stars). Thank you, ***** ***** luck to you!