What is the ruling on shunning the husband's brother's wife who initiated the shunning and raises suspicions with her interaction with the husband, given the severe mixing and lack of hijab among the women in the husband's family? And how can the wife atone for her anger and estrangement with her deceased mother-in-law, due to the latter's command to her to greet her brother-in-law's wife, knowing that she was dutiful to her before that?

Family intermingling without lawful boundaries is a dangerous matter, and it is obligatory to advise those who practice it with wisdom and good admonition. If your brother's wife deals with your husband in a way that raises suspicions, she is committing a reprehensible act, and you must advise her directly or through someone who can influence her. If she persists, then the permissibility of shunning those who commit sins is established, while considering what is beneficial. What has been mentioned applies to the daughter-in-law of the aunt.

If your husband is lenient with non-mahram women, remind him of Allah's punishment, and that he must close the doors to Satan. If he continues in his state, his transgression permits seeking a divorce, but do not rush into it, as it may not be in your best interest.

Regarding the dispute with your mother-in-law, if you have not wronged her, then there is nothing against you. If you have fallen short in her rights, then supplicate for her frequently and ask Allah to unite you both in Paradise.