nursing/bottle strikes are common with a mom's return to work, or a switch over to bottle.
what you need to remember is that baby will not starve herself, but she will want to hold off on eating until you are back again. this might make your mornings and evenings a bit more complicated, but for the time being, do your best to give her the security and love of your nursing her when you are there. cosleeping is a wonderful option as you will both just go back to sleep, but she will be able to recreate the closeness and eat during that time. i did it with my son and i dont regret one second.
try having the person who feeds her sit in a different location than the place you nurse. that might help. things that remind her of your breast will make it difficult for her to take the bottle.
anyway, just have patience. like i said, i highly doubt she will starve herself. and GREAT JOB MOM FOR BEING AN UNDERSTANDING, BREASTFEEDING, COSLEEPING MOM!!! :D
www.askdrsears.com is a good resource.