I just fucked a girl in my office

I am a teacher in a high school,in my office,there's another beautiful girl who has a crush on me.I have a little bit like her too.As time goes by,I think I am in love with her.So one day,we went out in a hotel and made love.That's a beautiful thing,but the problem is she already has a boyfriend,she was confused,so was I.I don't know who was hurt in this complicated thing.shit!