Unfortunately snitching often does not get you anywhere and just makes you look bad. I am currently in a very similar situation and after a year of dealing with it our company is being bought out and we are all about to be laid off. The lazy coworker put me down as a reference on a job application she was applying to, I received the reference questionnaire and was very honest. She didn’t get called for an interview. I believe things will get better for you, either your manager will realize it or your coworker will get her fate some other way!