Contrary opinion here, you did wrong. She messed up when she called you knowing where you were and what your were doing. She should have locked the door and called the police. Since she wasn't sensible enough to do that you should have called the police. I'm glad it worked out but this could have had tragedy all over it once he realized nobody called the police and all you were was a distant voice on the phone and not an immediate threat to him.
Good intentions will always be pleaded for any assumption of power. The Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern will, but they mean to govern. They promise to be good masters, but they mean to be masters.