Have you attended any meetings in your area ? alanon, coda, naranon ?
the first step is to admit that you are powerless over the addiction, etc. ... it's tough letting go but if you wish to retain your sanity - you will search until you find what will work for you and detach as best you can.
I'm sorry that you are struggling and that your brother relapsed but please read as much as you can and seek help for your own recovery.
i will keep you in my thoughts and prayers. Hugs to you
