Have you ever found yourself bullied at work and what did you do?

I am getting increasingly depressed. I work in a small Customer Services team and the girl who sits next to me has been subtly hostile from day 1 - excludes me from conversations, makes remarks that I eat too much, tries to belittle me. The one time I did stand up for myself I ended up having to apologise for "snapping at her", so I just try to ignore her as best I can.
Unfortunately she is responsible for dishing out the work, and she gives me less and less, and keeps all the best work for her and her work buddy. I have asked my manager about this, but she is like the golden girl as far as he's concerned (she is also tall, blond and very attractive). She can do no wrong!
I am becoming increasing demoralised... I dread going to work and I can't afford to walk out without a job to go to.