My first real doubts

I remember in nursing school they told us that nurses eat their young. I kind of laughed and said that yes, I'd heard that. Well, now I know what they meant; someone is trying to bite a little bit off each time I work now. All through nursing school clinicals and most of my orientation in the Burn ICU where I work, people were pretty patient with me, seeming to understand that I am a new grad. But then there is this one. Not even an 'old timer'. She's younger than I am, though has about 5 years of nursing experience. She seems to be a really good nurse, but is so openly rude and impatient to me- lots of eye rolling, snide remarks and not-quite-behind-the-back snarky comments. I think she is unreasonable to expect that I can flow like an experienced nurse and handle our sickest patients without getting behind or asking questions (she is usually charge when she works). Should I, after 3 months, not have anymore questions? It's true, I do ask the same questions over sometimes, but I'd rather ask repeatedly to double check and do the task correctly than not ask and cause damage. But it doesn't matter which I choose because she will tell me I am wrong, she will roll her eyes, she will speak rudely and sigh loudly - in front of coworkers and patients. I am not the type to run and tell; I would like, in fact, to "turn the other cheek"; but my barely-there confidence is waining and for the first time, I am truly wondering whether I can handle working in an ICU. Maybe it IS too much coming right out of school; especially out of an accelerated program. I hate to think of giving up, but I feel like a complete moron most of the time. Should I start looking for another unit?