Is advising the mother who wrongs my brother's wife an obligation upon me as a form of righteousness, even if it leads to embarrassing her and her invoking curses upon me?

Part of showing filial piety to one's mother is to advise her gently. However, embarrassing her in front of people and demanding that she supplicate against you contradicts the principles of showing kindness, lowering the wing of humility to her, and accompanying her with goodness, as Allah Almighty says: "And We have enjoined upon man [care] for his parents. His mother carried him through weakness upon weakness, and his weaning is in two years. Be grateful to Me and to your parents; to Me is the [final] destination. But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them but accompany them in [this] world with appropriate kindness." And His saying: "And your Lord has decreed that you not worship except Him, and to parents, good treatment." The mother is the most deserving of people of good companionship. And a parent's supplication against their child is answered. Therefore, one must be careful not to incur the supplication of your mother.