What is the reason for feeling distressed by one's sister, alienated from people, quick to anger, and losing the desire to do beloved things?

The Prophet, peace and blessings be upon him, forbade turning away from each other and mutual hatred. The people most entitled to this (kindness) are family members. Therefore, the questioner should seek refuge with Allah from Satan, strive to maintain ties with her sister and preserve her affection, exhibit good character towards everyone, and endeavor to acquire the means for increasing faith and expanding the heart.