Claim of duress

what must be proven to claim that a contract was signed under duress? If ex had info on tape that she threatened to use against me if I did not sign sep agreement is that duress. She threatened to use tape stating it would prevent me from seeing children, possible loss of job. Would a judge consider this duress?

No, the legal definition of duress is much stronger, you must prove that you signed the agreement because you where under an imminent threat of serious physical harm.