How do you cope with a break up after a long term relationship? Especially if we still have class together.?

We have broke up about a week ago and we dated for 5 years. We are both 21 and have two college classes together. There were talks of marriage and I picked out an engagement ring and was paying on it recently. We had plans of going to med school together. It all went south in about a month. I didn't want the break up. There isn't another guy for her, nor a girl for me, at least for a while.How do you cope with a break up after a long term relationship? Especially if we still have class together.?
Soo.. i'm confused. Who broke up with who? Why? If you guys just broke up, do you want to get back together? Does she? If you don't get back together, you can either start short-talk and try rebuild a friend relationship otherwise you'll just have to accept it and move on.