What is the fatwa regarding a husband's oath to divorce his wife if she enters his brother's house, knowing that he has reconciled with his brother and she has not yet entered his house? And does the divorce occur if she enters it for occasions?

The husband made your divorce conditional upon your entering his brother's house, using the phrase "you are considered divorced." This phrase is one of the euphemisms for divorce, and the divorce takes effect if he intended to pronounce it and you enter his brother's house. The cessation of the dispute does not have an effect because it is due to an action by the husband. The solution is for you not to enter his brother's house, otherwise the divorce will take effect.