I wouldn't worry unless you really really in love with her and such. There's always at least few other fish in the sea or other people you can learn to love in the same way, however if you really don't think thats the care and want her back...maybe this new boyfriend is just a fling and won't be anything serious. Just don't go around all day sulking, remain calm and see if the wind one day blows the two of you back together. For now, try to have some fun!

Knowing yourself and your capabilities is the first step to getting through this without incident. I agree that it is best that you know she has moved on. It doesn't help you emotionally because feelings are something that have a mind of their own, but I think it's best to just take one day at a time.

I know you will be ok, especially since you seem to know yourself. If you do think you are going to have a breakdown, make sure you have your parents or a buddy to hang out with and that will make it easier. Better yet, don't even wait for that: talk it out with a friend who you know will give you the support that you need.

I'm sorry that this happened to you, but things will be looking up soon I am sure