"My brother and I, we really hate each other."
Translation:Mon frère et moi, nous nous détestons vraiment.
Since no French speaker has clarified this, I did some more research and according to francais.lingolia.com, it can be placed before or after the verb, however the meaning changes with it. The adverb vraiment can be placed before or after the second part of the negation, however, the meaning of the sentence changes. Examples: Elle n’y connaissait pas vraiment grand chose. → She didn’t understand much about it. Elle n’y connaissait vraiment pas grand chose. → She didn’t understand anything about it Full website here: https://francais.lingolia.com/en/grammar/adverbs/placement#:~:text=The%20adverb%20vraiment%20can%20be,connaissait%20pas%20vraiment%20grand%20chose.&text=Adverbs%20that%20refer%20to%20adjectives,adjective%20or%20adverb%20in%20question.