Is it religiously permissible for a man to marry his maternal uncle's wife, who wishes to divorce him due to his mistreatment of her and their two children, and what are his rights and obligations towards her two children?

It is permissible for a man to marry his maternal uncle's wife if he divorced her and her waiting period (iddah) has ended, because she is not among the unmarriageable relatives (mahram). It is forbidden for him to establish any unlawful relationship with her or to incite her divorce. However, if the divorce occurred without any suspicion on his part, then there is no harm in marrying her, and he must treat his maternal uncle's children kindly and maintain kinship ties.