Chapter 8: Finally Revealed

I text Sarah everyday as usual, but the essence of our messages is blatantly off. She can tell that something is wrong, and I know that I should tell her, but I just can't bring myself to do it.
I get a text from Sarah, "Can I tell you a secret?" My heart races, as I open her next message, which says, "I like you. And I think you like me." I pause, thinking this through. I had completely spaced the fact that I had a boyfriend at the time, and once I remembered I decided to tell her that I had a boyfriend, versus the fact that I liked her, too. She seemed genuinely upset by this fact, and went on to say that she was sorry and she never should have liked a straight girl. She left and didn't talked to me anymore that day.
What had I done?