Is a marriage considered secret if it is conducted with witnesses who have agreed to keep it confidential, and is the wife entitled to claim her rights after the husband agreed to receive a promissory note from her relinquishing her rights?

You made a mistake by leaving your family and marrying without a guardian, as the majority of scholars stipulate the presence of a guardian for the validity of the marriage.

You must repent and return to your family. If the husband does not divorce you unless you relinquish your right to the dowry, then do so, because you cannot marry anyone else until after his divorce or the annulment of the marriage and the completion of the waiting period.