Is my decision sound to visit my family alone without my wife, believing that things will improve with my sister's marriage, especially since they do not desire my wife's presence and do not ask about her, and this is to avoid wronging her by divorce and disobeying my parents?

If the reality is as you described, then you were right to visit your family alone for the common good. You must be diligent in honoring your father in all circumstances, and you are not required to divorce your righteous wife. We advise you to seek wisdom and strive to remove whatever disturbs the purity of the relationship between your wife and your family.