Me and my twin brother are now in a huge fight.?

So what is funny is we are both dating a pair of twins so... I made a date to "make out" with my girlfriend and on the way there I met you guessed it my girlfriends twin well... you guessed it she thought I was him and what turned from making out we actually had sex instead so... we found out after she was moaning my name witch you guessed wasn't my name well... My bro got mad my girlfriend also got mad but she didn't really get in trouble with my brother but my girlfriend dumped me what should I do to convince it was an acciedent. Because one thing is she told and she lied and said I tricked her WHAT SHOULD I DO.