Since your mom is so old fashion, it would be in your best interest not to say anything right now. Just remember that as soon as you reach adulthood you going to have to move out. You can help your mom by giving her something to read about homosexuality, and even though she might be disgusted, eventually she would understand. I bet she is a very religious woman and those are the hardest to understand. Remember to stay strong for your brother. It would be helpful to remind her that homosexuality is innate and not acquired, there is got to be some one else gay in the family dig deep (no pun intended)