Does the debt remain upon the deceased whose creditor forgave him before his death, then retracted his forgiveness thereafter?

Whoever relinquishes their share (in an inheritance) in the presence of witnesses, their retraction is not accepted unless there is evidence proving that the relinquishment was not genuine, and that this evidence was witnessed before the relinquishment and for a reason. If your father's maternal aunt secretly had witnesses attest before the relinquishment that she did not mean what she said, then she has the right to her share of the inheritance; otherwise, she does not. It is good for you to appease her due to kinship ties.