Yup.....it's my dad's birthday, so my oldest sister and my niece came over....apparently he called her up freaking out about me planning to move after I turn 18 (completely separate issue) and outed me asking her to try and talk me out of it. Luckily she is extremely supportive, has gay friends, and has been to gay bars and stuff. She also encourages me to travel so long as I'm ready and prepared. Luckily this didn't go bad.
It wasn't fair to you that your dad outed you but at least your sister took it well so that's a good thing!
You might want to have a calm, civil chat with your dad about how outing people is rude at best and dangerous at worst. Yes, he only outed you to your sister and it's GREAT that she understands... but what if it had been to a homophobic buddy? Stuff like that can get people beaten up or worse. I'm happy your sister is supportive, but yeah... might want to discuss GLBT etiquette with your dad.