Call project YES in Brooklyn. They provide help for siblings of OTD kids.
You are not alone. There are many kids that are OTD and it is very hard for the parents and siblings. But this will make you stronger and you will have alot of understanding and ahavat yisroel for every Jew. Daven to Hashem that he should help your brother come back to Yiddishkiet. Hatzlocha!