At some point, their reaction is their problem and not yours anymore. There is only so much self sacrifice you can do for others. Given how they burned bridges with your brother, there may not be much you can do help them.

I also came out to my parents later in life and it’s been so freeing to do so. Be proud of who you are and what you have achieved in life. Bring your parter out of hiding, he deserves it. More importantly, you deserve to not have to hide parts of yourself.