Does a divorce that occurred under threat of death take effect, and is the wife still lawfully bound to the man, and would she be considered an adulteress if she married another man in this situation?

The divorce is valid due to your acknowledgment of it before the Ma'dhoun (marriage officiant) without coercion. You could have informed the relevant authorities or stated that you were coerced. Since you acknowledged and went through with the divorce, it is binding upon you. You may, however, take your wife back before the expiration of her iddah (definition) (waiting period) if this was the first or second divorce.