What is the ruling on the supplicant not asking for forgiveness from someone he wronged, despite his repentance and regret for the sin, and his fear that his life would be destroyed if he broached the subject with him?

You have not clarified the nature of the injustice you committed against your husband. If the injustice was taking his money without right, then you must return the money to him, even if indirectly. If the injustice relates to his honor, the default is that you should ask for his forgiveness. However, if you fear a greater harm, then supplicating for him is sufficient. If you have committed an act of indecency, then concealing yourself is obligatory, and you should not inform anyone of it.