Welcome to SR......I hope you find strength and support here.
It's very very hard to watch someone do the things that drug addicts do. And it's very difficult to deny them when they are using powerful guilt tactics. It's hard to even consider standing by idly while they endure the consequences of their addiction and lifestyle. It's hard to say "no".
It's very powerful to hear (or read) that it's ok to let the addict face their own consequences and that we aren't to blame for the outcome. And it's very important for the addict to have the opportunity to dance with their addiction alone.
I'm sorry that your brother's addiction has affected your family but you hit the nail on the head. You have your own family that needs your love, support and attention. And that's ok.
You and your dear brother will be in my prayers.
gentle hugs
ke