What is the way to deal with a brother who mistreats with harsh words and light physical striking when angry, and how can one avoid the impact of that on preparations for Ramadan and worship?

We advise you to be patient and supplicate for your brother's guidance. You do not incur sin if you reciprocate his offense in kind, in accordance with the verse: "And the recompense of an evil deed is an evil deed like it." However, forgiveness is better, and its reward is with Allah, for His saying, the Exalted: "So whoever pardons and makes reconciliation - his reward is due from Allah. Indeed, He does not like wrongdoers." Therefore, we advise you to be patient and forgive, and not to reciprocate evil with evil. And beware of boycotting him, especially in Ramadan, due to the Hadith: "If someone insults him or fights him, he should say: 'Indeed, I am a fasting person.'"