Most all the advice given is appropriate. And, you need to realize that when you go in to a unit where the nurses have been there forever, it is their territory and they are VERY territorial. They have never tried anything else and are stuck in a rut and don't have the guts to try a different unit. If it gets too unbearable, ask for a transfer to another unit rather than leaving the hospital all together. These people will never change, every hospital has them. My family moves around a lot and I have been the newbie on the block more times than I can remember and there is always several nurses like that and ones in specialized fields like ICU, CCU, etc. are worse than most.
Get some counseling because of your background, and all of this may be slight over-reaction to their comments and internalizing their sarcasm rather than letting it roll off your back which you will have to learn to do if you are going to survive. And lastly, chronic sleep deprivation makes you much more sensitive to what others say and do. With very little sleep or quality sleep, I can cry at almost anything (but, I never let them see me cry at work!). Lack of sleep affects your attitude, your mood and your ability to cope.
I'm sorry you are going through this right now but with a few changes (counseling, speaking up, visiting with your manager, quality sleep) you may be better able to cope with this work environment. We are all pulling for you.