Dear emags my thoughts are with you. I can't believe you are faced with this situation so young. I find things hard enough with my husband with dementia - but to have it happen to your mother, when you are still at an age to want and need mothering yourself - it is unbelievable. I know that feeling of them being "there - yet not there." With my husband, he's still himself - but not completely himself. He's diminished. And you have been watching this for over five years! My heart goes out to you.
It is perfectly understandable that, being away at university, you feel torn and wish you were at home. But no mother in the world would want that. We would all insist on your staying at college, living your own life - and thinking of us from time to time, but always in a way that puts yourself and your own needs, your own life, first. You must do this for your mother's sake as well as your own. I believe that, as your Mom it is what she would most want, if she were still as she was, even though, sadly, she isn't now.
The feeling of being torn will be with you always, on and off, in lots of ways. When my children were young, and I was at work, I longed to be with them. When I was home, I worried about not being at work. It is a sort of ambivalence and it comes form leading a rich, fulfilling life, in which there will always be competing needs. Right now, your paramount goal, despite this ghastly situation, is to get on with your studies. Thinking of you. Carolyn.