Hi Teddy,
I know the reactions you got from family really sting, but initial reactions are not final reactions. They don't get it because they have absolutely no concept of what it's like to be transgender, so from their perspective your choices are idiotic and wrong.
When my wife and sons found out I was transgender, it was by accident and I found myself in a vey defensive position instead of the carefully managed scenario I had envisioned. We had a family sit-down, and it did not go well. My youngest son (he was 10 at the time) was kind of silent, my older son (then 13) told me, "Just don't do 'that' [looking like a girl] in front of me", and my step-son (then 20) refused to even be present. He later texted me and told me that I "was an embarrassment to the family" and I "should move far away so I don't screw up" my younger sons. My wife was not hostile, but it was clear she was trying to "protect" her children rather than help me, or help us as a family.
Fast-forward two years later, and my wife is civil, but distant. My youngest son and I are very close, and he accepts me fully. My older son tolerates me now that I am a full-time female, and will call me when he wants something, but would die of embarrassment if his friends saw me. My step-son is as angry as ever, recently telling me I "f****d up his life and my family's life, and all his memories about me are a lie". There was more to the diatribe, but I think you get the gist of it.
It hurts, obviously, but telling my step-son how wrong he is or pointing out the hypocrisy of his views would fall on deaf ears and only serve to reinforce the breach between us. I don't want a failed relationship but I am what I am and it took a tremendous amount of courage and personal strength to get to the point where I can live as my authentic self. I have nothing to apologize for, and neither do you. Play the long game, with the hope that in time there will be reconciliation. If there isn't, so be it.
We are all stardust. At the end of our days, the flesh will fall away, and we will return to that from which we came. All that will remain is who we really are. These few short years on this earth should be lived as best you can.
The only advice I can give you Teddy is to keep love in your heart as much as you can, give your parents and brother time, and be the person you know you are. The rest is up to them.
With kindness,
Terri