Pinsir I have nearly the same situation. There is nothing you can do to console your mother. I have been "out" for more than 10 years to my parents and still they are devastated because they believe I am going to hell while they spend eternity together. While ridiculous, it's understandable given the presupposition.
It will become less sad for her, though. Time will help. What you must do is to continue to love your mother, being firm in yourself. My mother still tries to guilt me into "being with the family" for Christmas or Easter services at her church. Advocate for yourself while remembering that you only have this one life with your family, don't allow this to drive a wedge between you. Also, support your little brother. I'm not sure how old he is, but it can be rough being younger and not having someone to talk to about this stuff.
It will become less sad for her, though. Time will help. What you must do is to continue to love your mother, being firm in yourself. My mother still tries to guilt me into "being with the family" for Christmas or Easter services at her church. Advocate for yourself while remembering that you only have this one life with your family, don't allow this to drive a wedge between you. Also, support your little brother. I'm not sure how old he is, but it can be rough being younger and not having someone to talk to about this stuff.