Feeling down and upset

For the past couple months I have been getting bullied at work by this one girl. I work at a group home and I work overnights so there is only 2 staff on during a shift. I work with 2 different girls and one is my best friend, we hang out outside of work and she is invited to my wedding etc. The other girl is newer (not finished her 3 month probation period). She is very lazy and not hardworking like I am and that bothers me because I constantly have to pick up her slack and with only 1 other staff on shift, it makes it very tiring for me because the shifts are between 9-12 hours and sometimes I don't get a break because of her. I made the mistake of venting to one of the other staff about this new girl being lazy and because of it, I didn't enjoy working with her... this staff went to her and told her and ever since she has been bullying me. She has yelled at me on shift, she said that nobody at work likes me and staff get together in groups and talk bad about me, she said that people call me the Nazi which is completely disrespectful, she said that she doesn't understand how my fiancé who is so religious could be with such a mean spirited girl like me who probably treats him like crap which honestly really hurt my feelings, and then the other day she called me a "c u next Tuesday" to put it politely. She also told me my friend Sarah hates me and wants to quit because of me. I am deeply hurt by everything she said, because I felt bad for talking behind her back instead of just confronting her, and so I apologized to her and admitted I was in the wrong and I should also have given her a fair chance. Now she just verbally attacks me and is always putting me down. Anyways I had a meeting with my supervisor to report the bullying and this girl denied everything she has said and lied about it all. She also has been telling other staff at work lies about me which is hurting my friendships. I also had another staff go to my supervisor to say I am being bullied on shift and yet nothing is being done about it. I came home crying Tuesday and am scared to work with this other girl and because of it I need to quit my job. I feel like this couldn't have happened at a worse time because the wedding is in August and all the payments are due next month and trying to find a new full time job with benefits and willing to work around the fact I have a wedding and honeymoon booked and two weddings in September, is just really going to be hard and I just don't know what to do. I am feeling super down the past week and just needed to vent.