How is your relationship with your brother/sister who was also raised by a BPD mother and an enabler?

I lived under the false idea that common experience would bring us close but my brother thinks I was awful to him as a child - I have no memory of those years but I know I wasn’t very nice at least - and has been treating me with bitterness over the last few years. I have apologised a lot but I also feel like I don’t deserve to be treated badly for things I did as a child that was severely mistreated herself. He seems unable to have a conversation with me without thinking I’m criticising him and proceeding to criticise me. I have expressed my support and interest in his life over the past few years while he doesn’t know a thing about my life… doesn’t seem to care. I don’t know what to do to mend things. Are they fixable? This puzzles me because I’m usually quite good at seeing how things can be fixed (that is with people outside family). But here I have no clue. This whole family is a sad joke, everytime I’m here I feel suffocated and just sad that this was the family I got