So...if you look at my profile it says I am gay, which is true. I plan on coming out soon, I'm already out to close friends as bisexual (whoops) and my closest friends as gay. All that went great, and I am finally comfortable with myself to let everyone know. So, I had this girlfriend my bad just to stop rumors that I was gay (because I'm kinda...really a lotta fem) and that worked. We broke up and we are still friends, but she goes to a different school now. She didn't know I was gay. What do I do, because one way or another, she will find out.
The only advice i can give you is to try to talk to her before someone else could tell her about you and trashtalk about that. You said that you broke up but are still in good terms, so I'm pretty sure that if you'd come out to her, she would still respect and be your friend anyway, so maybe it could be worth to give a try and talk. Good luck!