I dont have much advice for you, except to say that as a mom I know where you are coming from ( I tend to see my own children when I look into teh faces of kids who are suffering.)
It is a good thing that you are saddened by what you see-this is what will make you a good nurse. But, you also need to make sure you are supported and can talk about what you see and feel!
Something that helped me when I was a CNA was taking a moment with each patient and saying a little prayer for them inside my heart. If you dont pray, maybe you could just have a little moment of silence for each person you encounter and wish them happiness, health, etc. As a religeous person this helped me put things into perspective.
I have learned (and am still learning) that I cant fix everything, I cant explain why bad things happen, and I am helpless in many aspects. But, I can say a prayer, do my best in my job, give excellent care, protect my patient as much as possible, and offer a hug, a touch, etc.
Good luck to you! (Good luck to all of us who are students!! )