If your brother remembers something different, that doesn't mean that what he remembers is "correct" and what you remember is "incorrect." The tricky thing about memory is that each of our brains each constructs it, so even a non-traumatic event can be perceived differently by two people. Add in trauma, and it's confusing.

I do suggest that if you talk to this brother to further learn about his memories and to try to corroborate or expand your own, that you do it with a T who can help you and is looking out for you, so to speak.