I think what you need to keep at the front of your mind is all the stuff you said in the last paragraph: a relationship where you argue loads and that makes you feel trapped, hurt and stressed isn't one that you should be staying in, regardless of university.
I know from personal experience how easy it is to get almost addicted to the ups and downs of arguing and then some sort of passionate make-up, it's an endless cycle, but long term it makes you miserable. I also understand that despite all the arguments, you care about him, if only for being close to him for that long. However, from the way you've worded your post it is about feeling loved and needed again and not about this particular ex. I think everyone feels like that after coming out of a long term relationship actually, just because you take it for granted that you're needed and it can be a bit of a shock when you aren't any more.
However, from what you've said I don't think you need him any more. You don't need an emotional (yet unhappy) relationship to give you self worth. Hell, you don't need a man at all! Try to sort of rebuild your mindset around being a singleton again. Concentrate on going to uni and remember not to get yourself a reputation as a bit desperate in fresher's week. That won't help the self worth issue. It might take a bit fo self control for a while (after my similarish dysfunctional relationship I pulled ridiculous amounts of people - it made me feel rubbish after a while), but soon enough you should be back to normal. You know you can have a great time without him, so make sure you do that. And next time you enter a relationship, I'd avoid the over-emotional, crying down the phone type. Maybe it's just me but I find them so stressful.
Good luck!
Cxx