Oh, baby.
The sibling bond is stronger than any ideology or dogma. Just know that there are men and women out there who come out and go on to have great, successful, happy lives. My brother and I took my other brother's coming out just fine, and my brother R was a bit of a homophobe.
People change their unfounded views.
Being gay or bi or straight is just a facet and is so unimportant. It's nothing you chose. It's nothing you can change. Are you in an area with good support groups? You have people here at least who love you and care about you and just want you to be safe. PM me if you need anything.