Does Allah accept the supplication of a wife against her oppressive husband who feels remorse inwardly, and is it even permissible for her to supplicate against him in the first place?

The prayer of the oppressed is answered, as stated in the Hadith (definition): "Beware of the supplication of the oppressed, for there is no barrier between it and Allah." As for the supplication of one who is not oppressed, it is an injustice and is impermissible. Allah does not love the public utterance of evil speech except by one who has been wronged. The husband who has wronged his wife should apologize to her and seek her رضا (رضا, contentment/satisfaction).