Be honest. Explain the situation, explain your mistakes in the situation, be sincerely sorry and acknowledge her feelings.

From a respect and ethical view that's what you should do, if practicality is your thing then put it this way: When you're sincere, honest and respectful to other people they're far more likely to be the same to you. If you play games with this then you're playing with fire, people are more likely to play their own little games. Social drama and bullshit flares up and suddenly something that could have easily been played down with a little honesty and humility becomes a ridiculous piece of typical soap drama.