Must I be dutiful to my maternal aunt who wrongs my mother, and would my dutifulness to her be considered undutifulness to my mother?

We thank the questioner for his dutifulness towards his aunt and his patience with her unkindness, for this has a great reward with Allah. The Prophet, peace and blessings be upon him, clarified that the maternal aunt is like one's mother.

Therefore, there is no contradiction between honoring one's mother and maintaining ties with one's maternal aunt. Continuing to maintain ties with her and being kind to her may remove the disagreement between your mother and your aunt. It is not permissible to cut ties with the maternal aunt, even if the mother commands it, for there is no obedience to a creature in disobedience to the Creator.