What is the ruling on continuing to maintain ties with a sister who has caused severe psychological wounds, and towards whom affection has ceased to exist?

Kinship ties are obligatory due to the verse: (And fear Allah, through Whom you ask one another, and the wombs/kinship ties). This does not mean reciprocating connection, but rather maintaining ties with relatives even if they cut them off, for the Prophet, peace and blessings be upon him, said: "The one who perfectly maintains kinship ties is not the one who reciprocates, but the one who maintains kinship ties even when they are cut off." A Muslim should seek reward from Allah for maintaining ties with those who cut them off, and Allah will be their helper and supporter, as stated in the hadith: "If you are as you said, then it is as if you are feeding them hot ashes, and you will continue to have a supporter from Allah as long as you persist in that." As for love, it is not required to love someone who wrongs you, but love for the sake of Allah must remain. A Muslim should never be utterly hated; rather, they should be loved in proportion to their religiosity and disliked in proportion to their sins.